When i was a kid, i broke or dislocated my left arm(not remember since i was very young). 2 or 3 months ago i noticed that my left arm joint which connects the shoulder doesn't feel right and swing properly and when i hold something(something heavy) and try to pull myself up(my arm bone makes me feel as if it will get out of my arm) my left arm bone  goes down but it doesn't occur with the right one. Please help me. I have no pain, but i want to use my arm efficiently. I know i couldn't bare the pain caused by dislocation, so it is not dislocated. But anyhow should i visit a doctor ?