Is the Tylenol 3 helping at all? It really isn't a very strong pain medicine...compared to oxycodone/hydrocodone, but it is a narcotic and should help take the edge off some.

Did you doctor offer any new testing or other suggestions other than give you pain meds for 5 days? Is there any way you can get your skin biopsy moved up from the end of May to something much sooner?

I would make sure you get instructions to try the Gabapentin when you go back to the doctor in a few days. And have him give you details to increase that dose as you need.