I Have A Sharp Pain In My Left Arm That

I have a sharp pain in my left arm that runs from my shoulder to my elbow. I have had it for 3 to 4 month's. I went to 8 physio sessions with only a little improvement. It hurts to put my arm over my head or even to throw something in the garbage. I have worked out with weights most of my life, just wondering what you think it might be?