Sorry I didn't see this sooner. I had similar pain and FINALLY had it diagnosed correctly by a pt. It was actually nerve compression, likely caused by bad bike fit. The pain originated at the collarbone area and radiated out toward my shoulder and down my arm. It worsened if I would nod my head downward. Not saying yours is exactly the same, but it could be a similar nerve thing rather than muscular/ligament thing. Whatever it is, best to get it diagnosed by a professional so that you can get on the road to recovery asap! Good luck to you!