This has happened to me as well. My doctor said it tends to hit
tall skinny men, statistically. I got the same condescending treatment from my docs, although the
culprit was a pack of unfiltered Camels.
People trying to hold their tobacco / pot / crack / meth smoke in will take a deep breath and hold it with a Valsalva maneuver. FWIW, we also do this every time we defecate. This puts stress on the lungs, and if you have any blebs or defects in your lung, they might blow out. The trauma-related version of this is what happens to Mark Wahlberg's character in Three Kings.
It feels like the end of the world. The key observation for those thinking, "Great: heart attack at 23!" would be that it hurts most when you breathe. Not that it matters when you can't get enough air.