Have you had your B12 measured? You need to be at 400pg/ml
at least (labs still report below 400 as "normal" and that is not.)

Long term low B12 damages the spinal cord...called combined degeneration of the spinal cord.

Here is a thread with links you might find helpful:

STICKY - The Vitamin B12 Thread:

People become low in B12 from vegan diets, taking acid blockers and metformin long term, and autoimmune attacks on intrinsic factor in the stomach (pernicious anemia).

Normal ageing can also lower B12. That is why many researchers now recommend a B12 suppement for those over 50 yrs old.

Military service people also can be poisoned from on base
toxins, over time. So getting tested for heavy metals and other toxins may be revealing for you.