Hi, my symptoms were burning feet and burning up to my knees, a Nerve Conduction Test showed absolutely nothing wrong as well, but Quanitive Sensory Testing showed mainly small nerve damage [the burning] and some large nerve involvement as well, by an EMG test.
I would phone that doc and tell them that you are getting no relief from the Gabapentin, and ask what do they suggest to do, as you really do need some relief.

Brian