i cracked my back for the first time in 9 months the other day, in the same way i used to do it in school when i would push off of my desk and crack it with the back of the chair. the next day i had what felt like a knot in the top of my back(which i don't think cracked when i did it) and tightness in my chest, also when i would lay on my left side holding myself up by my left elbow i would start feeling what seemed like my heartbeat right against my ribs. i could actually hear the sound, it was that loud. the next day my back felt better but not 100% annd my left shoulder started feeling like it was very slightly out of place, not painful to move or use, just annoying. is this anything to worry about...mostly the heartbeat part.