You aren't saying how many mg the tablets are, but you can go up to 3000 mg of gabapentin a day to deal with the burning. Most opioids will have limited usefulness with the pain. If you do want to go that route, Methadone does work because it is different and affects the NMDA (I think I have those in the right order) receptors. But still, best to use as little opioids as possible.

There are the antidepressants Effexor, Cymbalta, and a couple others that can be effective for the nerve pain as well. Have you tried any of those? I know it seems weird to take an AD but they do work.

Finding a multidisciplinary clinic would be the best. A trained PT can help you a lot with very slow progression of PT to work on desensitization to calm down the nerves. Mirror therapy can help with that as well.

Good luck.