I've been having the same problems with pain in my left arm for about two years now. What happened to me was, when I was at work. I had to lift a bottle jack out of the back of a pickup truck. I had to lean in over the tailgate to get it, about five feet or so. The jack was over 50 pounds. Instead of sliding it out to the edge of the tailgate. I tried to pick it up where it sat.. At that point, when I put all my force on it to lift it. I felt this (almost) like an electrical shock go through my arm. All the way up to my shoulder. about 20 min after that I felt this weird numb felling (right) dead center in the palm of my hand. It didn't hurt, it was just this weird fuzzy numb feeling about the size of a silver dollar in the center of my palm. That lasted for about (maybe) two hours or so. When I woke up the next morning my whole arm hurt from my shoulder down to my wrist. The pain wasn't severe. It was just this low dull pain, that was enough to (just) be aggravating. At night I couldn't sleep on it. This has been going on know for about two years. I will say that as time has gone by it has gotten a lot better, but it still comes and goes. I'm pretty sure I pulled a nerve. The Doc said there is a nerv cluster in both shoulders, just under the coller bone, that extends all the way down to your finger tips. He said these nerve clusters are like cell phone towers. They receive all the information from your hands , and send it to the brain. And then went on to say, that if you pull or pinch a nerve in your hand or wrist. the pain can resignate from where you pulled or pinched the nerve, all the way up to (these) nerve clusters. He said the best person to talk to would be a Nerosurgen. I have an appointment nest week. I'll keep you guys posted.