The good news is that (other than the pain) it is completely harmless.
The way it always felt to me is like someone wrapped a small wire around something tender in my chest, and if I tried to breathe or straighten my posture, they would yank on it. I’d get it anywhere from a couple times a week to once a month. Then one day in my mid-30s it just stopped.
From what I understand this is relatively common. I was so grateful for the person on reddit who dropped this nugget of wisdom several years ago. It was nice to know I wasn’t dying or whatever.
I have experienced this many times in my life. Was always terrifying and painful til someone posted something just like this years ago. Now it’s just painful. Still scares the crap out of my wife every time she sees it happen to me to though.