It is hard to say. But it seems that "something" is attacking your nerves. Autoimmune or toxin (drug) induced are the two main
causes.

Some hereditary PNs can be confusing too. If you seem to heal up from one location, and develop another, I'd think this would not be part of the hereditary picture.

You will want to look at gluten... this is a culprit too. Often overlooked.