Can someone with medical sports physio knowledge help me?

six months ago i was doing heavy weights and i mean stupidly heavy.i started to feel pain in my shoulder and across my collar bone,then this swelling appeared above my collar bone and at the base of the neck,so i stopped training to give it a rest but now when i life anything heave of if i do a lot of movement the swelling flares up and i det a dull pain around that area and down my bicep.is there a muscle that is behind your collarbone at the base of your neck