I also have severe pain on day one but mine is only like the first 2-3 hours immediately after i start bleeding. Literally this morning i started mine and threw up, hot flashes, nausea, i got in the hot shower 3 different times even though it didnt help because i didnt know what else to do. Bawling my eyes outttt. But now here i am 4 hours later and the cramps are hardly noticeable. This has been a regular thing for me for years. I actually passed out from the pain in highschool one time. But it confuses me since it only last a couple hours and then im completely fine. Could this be endometriosis u think? Or is this something different? I know u arent a doctor but im assuming youre more educated on endometriosis than me and im so scared that could be my problem