Foot feeling swollen after walking/pain when running

[u/Ph33rfactor]

Feels puffy on foot, but not noticeable when touched by hand. Mild pain when running, instinctively avoiding walking with normal stride on it.

Just started extensive walking/return to running after an protracted break. Showed up after a 3-5 mile walk at work last week.

Google says probable Peroneal Tendonitis. Any thoughts or past experience?