Thank you so much for your responses!
I tried the Benadryl when you first suggested it. It certainly allowed me to sleep better, but I am not sure it lessened my symptoms. I am going to give it a daytime trial for a few days when I do not have to teach, it knocks me out.
If the drugs are implicated, I agree that it is more likely to be the gabapentin. I have heard of people developing intolerances to medication after several years. I have been on 1800 mg for nearly 3 years. I think it would be worthwhile to see what happens without it, but I will wait until I have fewer obligations to try that.
I do take B-12, and fish oil. I had started with vitamin D but stopped when these symptoms started just in case it was part of the problem.
Since I have CMT, most supplements aren't going to make any difference, and it does progress, so this body-wide burning could just be the new normal. It just seems like it shouldn't be so sudden, and I am not sure that the doctor believed how life changing this symptom has been. I cannot get comfortable at all.

Again, this is very confusing and difficult to deal with and I appreciate both of you immensely.