I have a bruise on the inside of my bicep. Not very dark. It runs diagonally down my arm to the crease of my elbow when it stops. But, from the inside of my elbow down there is a raised line running diagonally to my forearm. the bruise hurts when I touch it. When I flex my wrist, that also hurts slightly. I do work out at a gym with weights, but no more than 20 lbs. what did I do?