I'm 52, and I still get PCS every so often, and have since I was a teen. It hurts like stink while it's happening, but if you take a very deep, full breath it causes the muscles that are cramping to 'pop,' or release, and the pain is instantly gone.

Something I've found through my own experimentation that helps when PCS strikes: grab your left ribcage with your right hand, and hold tight while pulling your left arm in tight against your body. Then breathe in deep and fast. It'll help with the pain as you work out the cramp that's causing the pain.

PCS won't kill you, regardless of the panicked feeling you get when it hits. It's NOT cardiac-related, in fact there's no known cause or treatment, and is considered non-life-threatening. It's just one of those minor annoyances that those of us that have it need to put up with every so often.