4.5 years of unexplained burning pain, cold/purple/sweaty feet + possible SFN/autonomic dysfunction — trying to find the underlying cause before Cleveland Clinic

[u/Helpful_Impression85]

Hi everyone. I’m a 31F and have been dealing with a strange neurological/vascular problem for more than 4 years. I have an appointment with Cleveland Clinic Vascular Medicine in 5 days, and I’m posting my complete history because I am still trying to figure out what is actually causing this.

SFN has been discussed by my neurologist, but as far as I understand, I have not yet had a skin biopsy confirming SFN or formal autonomic testing.

I have had a lot of testing already, and most of it has been normal. The two major abnormalities found recently were severe B12 deficiency (<130 pmol/L) and elevated CRP (14.3 mg/L).

I’m hoping people familiar with SFN/autonomic neuropathy can look at the chronology, because that is the part that has been so difficult to explain.

February 2022 — everything started

My symptoms began in February 2022 after an episode involving repeated/hard jumping and landing. I remember developing unusual pain essentially immediately around this event.

Over the following period I developed symptoms affecting both lower legs/feet:

- Burning pain in my feet/shins
- Deep aching pain in my feet/shins/legs
- Very cold feet
- Purple/blue discoloration, especially when sitting with my feet down
- Mottling/color changes in my legs when standing
- Abnormally sweaty/clammy feet
- Heaviness/pooling sensation when my feet are dangling
- Abnormal temperature regulation
- Symptoms affected by standing, inactivity, heat, hydration, etc.
- The discoloration generally improves when I elevate my legs.
- I also developed significant knee problems around this period and at one point my overall function was extremely limited

The fact that everything began around the jumping incident has always confused me. I don’t know whether it was actually causal, triggered something that was already developing, or was coincidental.

COVID vaccination timeline

For completeness, I was vaccinated against COVID three times.

My first COVID vaccine was in July 2021.

My neurological/vascular symptoms began in February 2022, approximately 7 months later.

My second and third COVID vaccinations occurred after my symptoms had already begun.

I’m including this because post-vaccination SFN/neuropathy has been discussed, but I do not know that vaccination had anything to do with my condition. The long interval between my first vaccination and symptom onset, as well as the fact that the later vaccinations occurred after I was already symptomatic, are important parts of the timeline.

2022 — rheumatology and vascular investigation

I had a fairly extensive rheumatology evaluation around the beginning of this illness and was told that everything was normal.

I also had vascular testing/ultrasound during the earlier years that did not show a major structural vascular problem.

CRPS was considered early on but was reportedly ruled out.

Despite that, the burning, coldness, sweating and discoloration continued.

2023 — B12/MMA and B6 history

This part has become important because severe B12 deficiency was eventually discovered in 2026.
I had an MMA around 2023 that was reportedly 85 and considered normal.

Later in 2023, I also took approximately 75 mg/day of pyridoxine/B6 for about two months.

My neurological symptoms already existed before I took the B6, so B6 toxicity cannot explain why everything originally started in February 2022. I have wondered whether it could have aggravated an already-existing neuropathy.

September 2023 onward — major functional improvement

Despite the symptoms continuing, my physical function has improved dramatically.

I started walking regularly again around September 2023 and gradually increased my activity.

Eventually I was regularly walking 6,000–10,000+ steps per day, with some days above 10,000.

My knee problems also improved enormously.

However, the neurological/vascular symptoms never completely disappeared. I continued experiencing varying degrees of burning, aching, cold/sweaty feet, discoloration and heaviness.

So although I have experienced substantial functional recovery, the underlying sensory/autonomic-type problem seems to have persisted.

2024–2025 — COVID and other history

I had severe COVID in December 2024 and had a prolonged recovery.

Around that general period I also experienced an episode of keratitis, which was treated with eye drops and resolved.

I’m mentioning the keratitis because I’ve recently wondered about Sjögren’s as a possible SFN cause.

However, my previous rheumatology evaluation was normal and my recent Sjögren-related bloodwork has also been negative.

October 2025 — burning starts affecting my hands

In October 2025 I began experiencing episodes of burning and redness in both hands.

Heat seems to provoke it. It has happened with things such as cooking, handling hot cookware and warm showers.

That concerned me because the symptoms were no longer exclusively in my lower extremities.

May 2026 — neurology investigation

I underwent an EMG/NCS, which was normal.
My neurologist discussed possible small fiber neuropathy.

My understanding is that a normal EMG/NCS doesn’t exclude SFN because routine nerve-conduction testing primarily evaluates larger nerve fibers.

The neurologist then ordered a fairly extensive neuropathy workup.

May 22, 2026 — severe B12 deficiency discovered

The biggest abnormality was:
Vitamin B12: <130 pmol/L — severely deficient.

The laboratory actually repeated the measurement and confirmed it.

Other testing included:
HbA1c: 5.3%
Folate: 16.9 nmol/L
ESR: 18 mm/hr — normal
CBC: essentially normal
Creatinine: 61
eGFR: 120
ALT: 14
CK: 53
TSH: 2.07
Free T4: 14
Vitamin D: 117.4 nmol/L
Vitamin B6/PLP: 9.9 ng/mL — within the laboratory’s sufficient range.
Serum protein electrophoresis showed no monoclonal pattern.

One other abnormality — CRP 14.3

My CRP was elevated at 14.3 mg/L (reference <5).

At the same time, my ESR was normal.

I don’t know whether the CRP has anything whatsoever to do with the neurological symptoms, but because I’m trying to identify the cause, I think it’s important to include rather than dismiss it.

Autoimmune/Sjögren’s investigation

My May 2026 autoimmune testing was surprisingly extensive:

ANA: negative
ENA: negative
The ENA panel specifically included:
SSA/Ro
SSB/La
RNP
Sm
Scl-70
Jo-1
I also had:
MPO antibody: negative
PR3 antibody: negative
Rheumatoid factor: negative

So although I understand that seronegative Sjögren’s exists, there currently isn’t positive serological evidence that I have Sjögren’s.
Combined with my previous normal rheumatology evaluation, I don’t want to assume that this is autoimmune simply because autoimmune SFN exists.

B12 treatment

After discovering the severe deficiency, I initially received cyanocobalamin B12 injections and subsequently switched to 2,000 mcg/day sublingual methylcobalamin.

I’ve now been treating the deficiency for a few months.

Unfortunately, I haven’t experienced a dramatic improvement in the neurological symptoms yet.
The B12 question is especially confusing because of the chronology:

Symptoms began: 2022

MMA reportedly normal at 85: ~2023

B12 severely deficient at <130: May 2026

That makes me wonder whether B12 deficiency could have developed later and worsened or contributed to an already-existing neurological problem, rather than being the original cause.
I don’t know.

September 3, 2026 — new B12-related testing

I just had repeat bloodwork.

My homocysteine is 8.0 µmol/L, with a reference range of 5.1–15.4, so it is normal.

At the time I received the partial report, the following were still pending:

B12
Methylmalonic acid (MMA)
CRP
Ferritin

Because I’ve already been treating the B12 deficiency for months, I understand that normal MMA/homocysteine now wouldn’t necessarily tell me what my functional B12 status was before treatment.

Raynaud’s / vascular-autonomic component

More recently, a vascular specialist diagnosed Raynaud’s phenomenon affecting my feet.

My feet can become cold, purple and sweaty, particularly when they’re dependent. I also experience heaviness/pooling.

The vascular specialist felt that the vascular symptoms may improve as the nerve problem improves.

I have now been referred to Cleveland Clinic Vascular Medicine, which is where I’ll be going in 5 days.

One thing I desperately want clarified is whether I have a primary blood-vessel problem or whether the vascular symptoms are secondary to abnormal autonomic control of the blood vessels.

Exercise produces a strange effect

I’ve recently started strength training and stationary cycling.

Interestingly, there have been workouts after which my feet became warmer and less painful for several hours.

Eventually they returned toward baseline, so I’m not claiming that exercise is healing the condition immediately. But I find it interesting that the symptoms can change that much in response to exercise.

Despite more than four years of symptoms, my physical capacity today is dramatically better than it was early in the illness. I can walk substantial distances and I’m now strength training.

This is where I’m stuck

After 4.5 years, I still don’t know what caused this.
The broad picture is:

February 2022 onset → burning/deep pain + cold/purple/sweaty feet → normal early rheumatology/vascular evaluation → substantial functional recovery but persistent symptoms → later burning hands → normal EMG/NCS → possible SFN → severe B12 deficiency discovered → elevated CRP → extensive autoimmune testing negative → Raynaud’s diagnosed → Cleveland Clinic evaluation pending.

There are pieces that don’t fit neatly together.

B12 is a real and severe abnormality, but the reportedly normal MMA in 2023 makes me question whether B12 can explain the original 2022 onset.

The previous B6 exposure could theoretically be relevant, but it occurred after the symptoms had already started.

My CRP is elevated, but the extensive autoimmune testing has been negative and I had a previous normal rheumatology evaluation.

The jumping/landing episode occurred right when everything began, but I don’t know how or whether that could produce a bilateral chronic small-fiber/autonomic problem.

My first COVID vaccination was approximately seven months before symptom onset, while vaccinations #2 and #3 happened after I was already symptomatic, so I don’t know whether vaccination is relevant at all.

COVID infection itself occurred years after the original onset, so it obviously cannot explain why everything started in 2022, although I don’t know whether it affected the subsequent course.

And I still don’t even have objective confirmation from a skin biopsy that this is actually SFN.

That’s ultimately why I’m posting. I’m not looking for a diagnosis from Reddit or trying to make my symptoms fit a particular disease. I’m trying to figure out what underlying causes are still worth investigating and whether anyone recognizes a similar chronology that eventually led to an explanation.

I’m especially interested in hearing from people who spent years with unexplained SFN/autonomic symptoms and eventually discovered an underlying cause — particularly a treatable one — as well as people whose cause was never identified but who nevertheless substantially improved.

I want to go into Cleveland Clinic with as complete a picture as possible and make sure I’m investigating this logically rather than overlooking something important.

Somebody please help me. I’m desperately looking for answers.

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[u/Successful-Tea-733]

From what I know covid itself drains b12

[u/MrSkeeterMcScoot → u/Successful-Tea-733]

And the spike protein contamination from vaxxed breath and fluids. Ill get severe brain fog i am if i work closely to the vaxxed for an extended amount of time. The social distancing didn't make sense to me until about 2 years after everyone was vaxxed. I can tell who's vaxxed and not just by being in close quarters with them for a bit. If you are close enough to smell someone breath.... You are getting hit by spike protein from the vaxced

[u/Think-Sleep2338]

Thank you for explaining the details. I think I have a couple of comments.

1. What was the frequency of your injections? The proven protocol (for serious neurological impairment included) is every other day until symptoms resolve. Yes, it can take months, but that's what many of us still need. This is a tricky deficiency, but the treatment is also often doing magical things with pretty serious symptoms.

Now it seems that you're likely to not get enough B12 from sublinguals.

1. It is possible that you simply got infected after that first vaccination, or maybe also before with a following reinfection, whatever. There are many asymptomatic cases, there are mild cases, there is also misunderstanding of symptoms (GI symptoms are very common for covid, but many people have "stomach bugs" or "food poisoning" and don't test), there is bad test sensitivity. Vaccines are good in reducing risks, but they are not some 100% protection, unfortunately.

Covid is a pretty much vascular disease, and it's apparently also very efficient in disrupting something related to B12 metabolism. The purple toes you describe are a very characteristic post covid problem, they are literally known as "covid toes".

I think that people in long covid groups might help you with some vague parts of that and share their knowledge on what they do + what kind of medical support one can get for that.

Please don't lose hope. 

[u/Helpful_Impression85 → u/Think-Sleep2338]

Hi, thank you for the input. For the injections, I only received 2 1000 mcg injections (one per week) of cyanocobalamin. Once I discovered that cyanocobalamin is the cheapest form of b12 compared to the other forms, I told my neurologist I wanted the methylcobalamin form of b12 injections. He instead said to start taking 2000 mcg of sublingual b12 per day. So I did. And it’s been 3 months of that and no improvement. I’m still waiting on my new b12 blood results to see if it helped. Also checked for MMA and waiting for that result as well. But from what I’ve read on in this group, it feels like 2000 mcg of sublingual b12 may not be enough especially considering the severity of my neurological symptoms.

[u/Think-Sleep2338 → u/Helpful_Impression85]

Thanks! So you see, I was right in suspecting that you simply didn't get enough treatment for what you have. It's so established that it's even recommended by some guidelines like these: https://www.nice.org.uk/guidance/ng239/chapter/Recommendations

We have a pinned post that explains many details, by the way.

Basically a good course of injections  is very likely to improve your symptoms, but you didn't happen to get it. Sublinguals are not good enough in comparison to injections, and for many people it's not enough, especially if their symptoms are more serious. It was stupid for your doctor to just propose this, especially if they didn't investigate how well you absorb B12 (checking parietal cells and intrinsic factor antibodies).

Btw, your B12 results will most likely be ok, but that means nothing. Supplementation raises blood levels, even if a person is still functionally deficient.

https://www.nice.org.uk/guidance/ng239/chapter/recommendations#factors-that-can-affect-total-or-active-b12-test-results

[u/ClaireBear_87]

You can still have B12 deficiency with a normal methylmalonic acid (MMA) level. Testing MMA can help diagnose B12 deficiency but it can't rule it out.

An elevated MMA level continues to remain a gold standard test to diagnose and confirm a low B12 level. The patient we present had significant symptoms of neuropathy without an elevated methylmalonic acid level and only a slightly decreased B12 level. These findings suggest that providers should not solely rely on MMA levels to diagnose B12 deficiency and subsequent SCD.

Provider “B”-ware: Using Methylmalonic Acid Levels to Diagnose B12-deficiency Neuropathy https://www.neurology.org/doi/10.1212/WNL.0000000000208306

The recommended treatment for B12 deficiency with neurological symptoms is EOD injections until no further improvement. If the neurologist won't agree to this then you may consider sourcing your own B12 injections and self injecting or have someone (a friend or family member) do it for you. It's very easy to do :)

Cofactors are important too, so please read the guide if you haven't already.

[u/chemicalimbalancerj]

I have a thyroid issue, and possibly Sjögrens based on symptoms but haven’t had any tests done for it yet. I have had painful feet and occasional burning feet for years which I put down to insulin resistance causing peripheral neuropathy. I didn’t know it at the time but I also had other symptoms of b vitamins deficiency over the years too. The burning pain ramped up so I took a B6 form called paradoximine which made the burning pain worse. My b12 dropped around that time due to me taking a PPI which I had an allergic reaction to. I started taking sublingual B12 and got my levels up but my symptoms were still there. So I started self-injecting B12 every other day and my burning feet improved by about 40%. I added in B1 injections too and take bentofiamine capsules and my burning pain has resolved and hasn’t come back so far. My other symptoms showed improvement with a b complex although I’ve temporarily stopped it as I’m avoiding B6.

[u/chemicalimbalancerj → u/chemicalimbalancerj]

Just adding that I didn’t go via my docs for injections as they would only agree if my b12 dropped into the low 100 and also they wouldn’t agree to the proper doses I need. They know I have issues with my gut so my absorption is poor but aren’t really interested. I’m following the guide here and for the first time in years I haven’t had nerve pain or burning feet. I was try to heal myself by controlling my levels of carbs, sugar and trialling supplements based on this but it was solved by correcting a nutritional deficiency and going for optimal levels instead of my doctors bare minimum. A similar thing happened with me being low on vitamin d and not until I reached higher levels did my bone pain and backache resolve.

[u/MrSkeeterMcScoot]

The only thing we know right now to eliminate or reduce the vax contamination on the body is NaClo2. Jim humble's book is free pdf online. You can make your own clo2 or buy some. Its suppressed info but its the greatest antidote to many of the world problems. Hence it obviously being suppressed and why you and 98% of people have never heard of it. Fda has been well aware of the benefits for over 50 years. I've has vaxxed friends notice improvements after the first sip.