I also have B6 and D deficiencies.

B6 deficiency is rare in the US because it can be found in so many foods. It is typically related to malnutrition, alcohol intake or malabsorption.

Vitamin B6 is unique in that either a deficiency or excess of B6 can cause neuropathy:

Pyridoxine Deficiency - emedicine

The Dana Guide

With an idiopathic deficiency, it is important to take the doses necessary to bring the levels up to normal ranges; and to monitor closely that the serum level doesn't exceed normal ranges. I started at 100 mg daily, but was still below normal ranges (2.9 with normal being 5 - 10), so was increased to 200 mg daily. I have not yet had follow-up blood test at this level. I have not noticed any decrease in the burning, but have had a noticible improvement in the brain fog that is also a symptom of B6 deficiency.