Originally Posted by mrsD

There are over 100 causes of PN.

You have to be a detective... look at food intolerances,
impaired blood sugar (doesn't have to be frank diabetes yet)
previous RX drugs that cause PN, toxin exposure,
something mechanically wrong in the foot, some nerve compression in the spine, hereditary influences, nutrient deficiences, exposure to vaccines, autoimmune disease, thyroid disease, etc etc.

You have to look at his life, recent past, in great detail to find the clues. He may need several tests, and alot of blood work.