Welcome to NeuroTalk!
I'm sorry for your pain. I have a dear friend with TN and MS and she takes Tegretol to control the pain. There must be something they can give you that won't cause an allergic reaction?
When will your insurance cover your pre-existing condition? Usually they have to cover it after one year? (I think that's the law?)
There are lots of wonderful people here and maybe somebody else will have some better ideas than mine. Take care and keep us posted.