I don't really have an answer for you, but I want to tell you I totally sympathize. I have chronic pain and was also diagnosed with fibromyalgia. I have a lot of problems with my back and neck which causes much pain in my arms and legs.
I think the fibro diagnosis is just a name they came up with when the doctors don't want to diagnose you for your pain. I'm no expert, but it sounds like you have rheumatoid arthritis, esp. if the methotrexate helps you. My sister has RA and it goes in cycles with flare-ups and periods when you feel OK. Your doctor sounds like an idiot to me. I agree that your previous doctor was at least trying to help you.
I have not found one doctor to take me seriously either. The rheumy I have just keeps saying fibro, and I think it's more than that. I don't take any pain pills--they bother my stomach and I don't want to get addicted, but now my pain is getting really bad and I may have to try--IF I can find someone to give me anything.
I understand about the quality of life. Mine is not too good. It is very difficult when you have to practically beg these doctors to help you. If I were you I would either go back to the other doctor or find a new one for another opinion.
It sounds to me like you need to get to another doctor. You were being successfully treated by your previous doctor. It is possible to be off of MTX for 2 months and still be ok and still have RA. There is also the possibility that you no longer require MTX to manage your symptoms and would be ok on plaquenil or another comparable medicine.
If your previous doctor does not know someone where you live now, try getting with a support group and finding out who patients recommend in your area. Please keep us posted on how you are doing.