A very similar thing happened to me, except it was ever intensifying stomach cramps. This is a known syndrome called Cannabinoid Hyper Emesis Syndrome. Something happens in the stomach where smoking weed chronically eventually creates some kind of chemical imbalance. The act of smoking begins to cause stomach aches that worsen with each dose. Eventually if cessation is not achieved, the cramps turn to nausea into vomiting that can become life threatening if you cannot stop smoking.

It's extremely terrible and the only known cure is to just stop smoking weed. I'm thankful for that now though because I've just been admitted to a PhD physics program and id've never made it this far while still smoking weed like i used to.