With all due respect, I'd like to ask you a couple things.

1) Did you use the RX form of D from your doctor? If so there will be little if any improvement. That RX is D2 and we now know it does very little. You need D3 instead which is OTC and the active form. Do you know your actual numerical reading result?
Also it is now estimated that about 80% of Americans are low in D. We have had posters on PN forum here get good relief from nerve pain with fixing D levels correctly. And even with the proper form of D3, it would take longer than 2 months to effect.

2) Did you ever have your B12 tested? Low B12 will cause nerve damage. Lab ranges in US are outdated and low levels are often not flagged, so doctors say "normal" when in fact they are quite low. The new lowest norm is now 400 pg/ml.
This is our B12 thread:
http://neurotalk.psychcentral.com/thread85103.html
This thread is long, but it has all the current new clinical data on it to help people with this common problem. The surge of acid blocking drugs OTC and long term use has contributed to
a rising number of people with B12 problems. This is because stomach acid is necessary to break cobalamin out of food so it can be absorbed.