pain between neck and shoulder

Because of a recent broken leg, I have been laying on my bed for most of the day. I have had my hand on my head leaning on my elbow. After about a week of laying in this position constantly, I noticed slight discomfort right above my left scapula between my neck and shoulder. Later I noticed when i move my arm behind me while keeping it close to my body a bulge would protrude out. It felt like muscle and when i pushed on it fairly hard it produced sensitive pain. I know its due to the way i have been laying down, because when i lay down now about 50% of the positions i have my arm in will cause that bulge to protrude and cause slight discomfort after a few minutes. The pain is not severe at all, but I would like to know what is causing this. Any help would be great.

Also the only thing since researching this has lead me to things such as, swelling of the coracoid, or supraspinatus.