Always assumed I had heart prolems

I've had PCS symptoms for as long as I can remember. My chest would randomly feel tight and hurt to take in deep breaths so I would just breathe in short quick breaths until the pain was over. Recently this lasted for almost 30 minutes and then my chest continued to feel tight like that for the rest of the day but it was not as bad as it usually is.
Around 6 months ago I was hanging out with my friend and we could just not stop laughing. And then out of the blue, the left side of my chest started to pop. I don't know how else to describe the feeling. It was sort of like a muscle right below my heart or maybe even in front of it started spazzing out whenever i would laugh. When I put my hand on the spot I could literally feel the muscle pulsing out. It is sort of hard to explain but the first word that came to mind mind was that my heart was "popping" out of my chest. This has only happened a few times since but when it has it is really annoying because I couldn't laugh without not having pain. But as far as I can remember, that is the only time i felt the "popping" feeling. I am only 15 and I am quite active and healthy so I don't think that my health has anything to do with why this happens.