Kitty, have they done MRI's and x-rays to confirm muscles, ligaments, tendons, and bones are all still normal? If that's the case you might want to see a pain specialist and let them begin the process of elemination.
Another option is a chiropractor, provided x-rays and MRI's are clean. Let him/her know of any pre-exsisting spinal conditions -- bulging discs, spine issues, neck injuries, etc. Frequently they will do an x-ray as well to check the area before working there. Sometimes numbness and tingling in one or both hands can be pinched nerves, and it also explains a measure of the arm pain.
However I had something similar. I had hurt my arm at work, my wrist. They thought it was just tendonitis, put me in a splint, gave me drugs, and eventually sent me to physical therapy. But the physical therapy made the pain worse. All tests came up clean, yet my arm was in intense pain, and I was having bouts of numbness in my hands. I know one doctor was concerned which fingers were experiencing the issues more as sometimes it can signal heart issues. However in my case, and it took several different doctors and two years, before I finally found someone who could figure out what I had/have.
I have CRPS, formerly known as RSD. It's a nerve disorder that you can look up easily on the internet. Mine started in my hand and wrist and over the years has spread to include my entire right arm and parts of my neck now. I would be more then happy to tell more, but lately my hand has gotten worse and typing is starting to become an issue for me.
Typical disclaimer: I am in no way shape or form a medical doctor or nurse. I do not claim to be such. I do not make diagnosis', I am merely pointing out a similarity in symptoms. Only a trained professional has the ability to make an honest diagnosis.