I had the very same experience as yours, except my pain and numbness crept up fro my feet to my buttocks in a matter of weeks. I've had 3 IVIG infusions and every test possible and still the doctors at Kaiser don't know whether my peripheral neuropathy is caused by an auto-immune disorder. I was also told that high blood sugar over a period of a few years can cause PN. Apart from Gabapentin and Vit D 3, I take insulin. I am now trying out The Institute for Health & Healing in San Francisco (**) and met with an Ayurvedic Dr. Akil Palanisamy. His first suggestion was to take stool tests to find out the condition of my gut. If your organs aren't functioning well they have difficulties in processing whatever you are ingesting. My aim is to slowly eliminate Gabapentin and Insulin (all meds) as these can also damage your organs. All this stuff and some herbs are very potent and may not mix well together.
One thing I've been doing recently, is to constantly massage and rub all the numb and painful areas with my hands (which are also numb and in pain) and I've noticed that my feet are looking more and more normal. My hands and fingers are able to write clearer and clearer, when at one time, I couldn't even hold the pen! Constant and varied exercises and activity may awaken damaged veins and nerves. This week, I am going swimming for the first time. I'll let you know how the Ayurvedic treatment and all this massaging and exercising works.