nerve pain in face

I am desperate for some type of solution to a problem that I have been dealing with for over 3 years. I was diagnosed with breast cancer and underwent chemo in 2006. During that time I had tenderness between two jaw teeth on the left side of my jaw. My dentist told me to use a small pipecleaner type instrument to get any trapped food out. This seemed to irritate the gum. The condition got worse with the nerve in that area becoming involved. I started having a feeling like hitting your elbow on that side of my face so I knew the nerve was involved. Since then I have been to dentists, oral surgeon, peradonitist, pain clinics, and neurologists. One of the teeth was extracted and the bone under it was bioposied. Two weeks ago I had root canal. It seems as if this just irritated the nerve more. Now my eye twitches, the left side of my nose aches, there is slight drooling, and I have a constant headache. The constant pain in my left temporal area is excruciating. The dentist prescribed 850 mg. amoxicillin which I started taking yesterday. I am at a lost as to what to do.