Have you looked at this website? It's from the Cleveland Clinic and may offer some clues:
http://peripheralneuropathycenter.uchicago.edu/faq/#gen8
Agree with Bill. I was diagnosed with "peripheral neuropathy ....... associated with diabetes" around 5 years post-tx. I had numbness in my toes spreading into my feet. It took a neurologist to catch the fact that I was insulin resistant - my family doc, who is diabetic himself, had always felt my blood sugar numbers "weren't that bad".
Besides taking an oral insulin sensitizer (and trying to be good with diet and exercise), my neuro' doc also put me on a fancy form of B vitamin compounded with a glutathione precursor (CerefolinNAC). This seems to have stopped the spreading numbness when even keeping my blood sugar under control didn't seem to be doing much good.
You sound as though you might have developed peripheral neuropathy; a condition often associated with diabetes. Has your blood sugar been checked? Do you have a history of diabetes in your family?
Bill