Has anybody ever heard of this pain problem?

I also have pain behind my left knee. It turns out that I have a Baker's cyst that gets aggravated with use and it hurts. The doctors will not remove it. I have to use ice and vibration therapy daily.
We have two main nerves coming from the neck down the arm: the median and the ulnar nerve. The one that you mentioned is the median nerve and it is probably pinched at the base which is in your neck. I had several nerve blocks and I am scheduled for radio frequency ablation (killing the nerve) to reduce the pain. Your pain doctor should be able to do this procedure under anesthesia and it should last for ~ 6 months. The nerve will grow back, but the pain signals should be less every time they repeat the procedure.

I hope this helps.

The inside the elbow pain is called golfer's elbow and the back of the knee pain is very common with arthritis. Isn't it fun to try to figure out our own ailments?