I've had several. Head straight to the best sports doc you can find. If it is a muscle to tendon tear there's not much they can do to repair, tendon to bone will require surgery. There are not alot of doc's out there in my opinion who are qualified in this area. After my first tear, tendon from bone, my doc said it would heal naturally........a year later after my attorney got involved I had it repaired at UF. I've had 2 muscle to tendon tears since. Do not try and work around it or use something to mask the problem. Being around the shoulder area, my guess would be a rotator cuff instead of a pec but get someone to look at it ASAP.
BPP