I have a mass that protrudes just above my clavicle on the left side. I have had both neck and shoulder injuries on that side. I suffer from compressed vertebrae in my neck and had a labrum surgery in the past. I've never fuller recovered from either and have had serious atrophy to that side and arm. The trap on the left side is bigger though but feels strange to the touch. Where as the right feels and looks healthy. I also have quite a bit of tightness in my left pec if that is relevant.