zoster virus

4 times this year, at 3 month intervals, I have had deep throratic pain followed by burning and shooting, acheing pain in my C7-C8 region. Sometimes pain will be in my arm pit, then move to my ring finger and little finger. No break out, lost 30 pounds, The first 2 times was the worst. I've had 3 MRI's and blood tests at a teaching hospital. No one has an answer. I think Herpes Zoster. I had a B 12 shot last week and am going to start Valtrex, one a day, to see if it helps. This is all on my right side. Air, temperature all affect this pain, Just like a constant sunburn and toothache in my arm. Can you think of anything else this could be? Or anything else that I could try to get over this? My Internist is not defensive if I come up with a question and he is willing to listen or try another approach. I have taken Fanvir 3 of the episods. Any help would be appreciated.