Really really painful sensation in between my chest and left shoulder?

It's like someone's trying to yank the muscle and nerves from my arm and its the tendon the is right on the left beside my chest leading from my shoulder. It hurts like he'll. Can you even pull the muscle from your armpit? All I know is that I feel like I want to cry from how bad it hurts. It's right beside my heart and admit, and I don't have any idea why. Maybe I pulled something? Any any any advice plz?