How To Treat Dislocation Of Muscles In Front Of My Shoulder?

I'm a 23 yr old female, and have a recurrent dislocating shoulder. The muscles in the front of my shoulder constantly twitch, and this is what causes the dislocations. Sometimes it is so bad that the spasms don't stop and I end up in hospital. What is causing this? I've had it just over 4 years, after something heavy pulled the shoulder out of the socket.