What medications can help with nerve pain caused by my multiple sclerosis? I have tried gabapentin and oxcabazapine and both have stopped working. 

Change dose. You might have built up tolerance and need dose escalation. Titrate Gabapentin to 1200 mg 3xday or 900 4xday. If alreadymat 3600 mg per day consider switching to lyrica (pregabalin).
Consider options. Dear ms lynch, a percutaneous trigeminal balloon micro compression can be very successful for trigeminal neuralgia with multiple sclerosis. This is a surgical "needle" procedure. Best wishes. Aoh.
Other choices. Consider Lyrica, (pregabalin) Cymbalta, even a Butrans patch. But do NOT see any basic MS drug on board. Did you forget to list it?
Still others. . Next in line would be Lyrica (pregabalin) and cymbalta. There are some others as well. Discuss your issues with your neurologist or who ever is managing your pain.
Others. Topiramate, pre-gabalin, lamotragine, any of the tcas. Typically, opiates are not the best for nerve and should avoided, but low dose Methadone may be an alternative. Talk to your doctor!