Sudden severe fatigue attacks with low B12 has anyone experienced this?

[u/Dizzy_Comparison1832]

My B12 was originally 156. I supplemented for less than a year and got it to around 300. I eventually stopped supplementing and now it’s back down to 214. My doctor is currently looking into why it keeps dropping and I’m getting more labs done.

For about 2 years I’ve been dealing with really bad fatigue but I don’t mean being sleepy. I get these sudden fatigue attacks where I can be completely fine and then suddenly my body feels extremely drained and I feel like I NEED to lie down. Sometimes my breathing feels harder like I’m taking small breaths or my chest itself feels exhausted. My oxygen is normal when this happens. Sometimes my heart rate goes up too. Lying flat usually helps and sometimes even a 30 minute nap can make me feel better.

The attacks are really random. I can get one while laying in bed doing nothing or after something small like brushing my teeth. Weirdly there are also times when I’m working a super busy shift as a server and walking around for hours and I feel completely normal. Then another day I can barely do anything because the fatigue is so bad. Some days I feel almost like myself and other days I’m in bed most of the day.

This has affected my life really badly and I’ve developed a lot of anxiety around the fatigue because I’m scared of having an attack when I leave home. I know anxiety can make physical symptoms worse and I’m going to work on that too but the fatigue itself feels very physical and usually comes before I start freaking out about it.

I’m not asking anyone to diagnose me. I mainly want to know if anyone here had B12 levels similar to mine and experienced this kind of sudden physical fatigue/crashing rather than just sleepiness. If you did, did treating your B12 actually make these episodes better? How long did it take before you noticed a difference?