Welcome to NeuroTalk:

What about medications? hobbies? exposure to chemicals in the garden or home?

While Dr. Latov's tests are pretty complete, there are not 100%
of tests available for everything. So some autoimmune peptide may be a culprit but there may not be a test for it yet.

Chemicals in the environment, can be problematic...even dry cleaning chemical residues. Chlorine in pools.

Then there is hereditary types, which have separate DNA tests not routinely done. Did you have any of these?

Were you tested for methylation failure?

Mechanical issues with the feet, or spine?

The first issues to look at are magnesium, B12 and Vit D. Your reading of B12 is on the low side. So taking some methylcobalamin for 3 months may show some improvement if that is your problem. Magnesium can be applied topically or used orally-- not the oxide form however since it is not absorbed.
You can try soaking in epsom salts and see if that helps at all.
For many here this helps and suggests further oral use or topical lotion.

If you take statins for cholesterol, you'll have to think about that...as they can cause PN. There are other drugs that can cause PN as well.