--have your been tested for cleiac disease/gluten sensitivity?

Often one of the first signs of this is malabsorption of vitamins/nutrients resulting in low serum levels--B12, D, B6, folate.

Moreover, celiac/gluten can cause neuropathy through autoimmune cross-reactivity all by itself.

Have you at least been titred up for anti-gliadin IgA/IgG (latter is lest specific but most sensitive), anti-transglutaminase IgA (more specific), and total IgA (as low levels can skew the other IgA tests)?