horrible period cramps/period gets clogged in cervix

This is such a weird thing that happens to me but I will try to explain it.

My period cramps have always been pretty painful (especially day two). But, about 7/8 months ago, day two of my period is so incredibly painful to which I can barley function. I’ve also been prescribed 800mg of ibuprofen by my OB GYN.

What happens is that my uterus starts contracting to the point where my lower stomach feels hard? AND THEN, i will stop bleeding for a few hours but with the most intense pelvic pain and pressure of my life. It doesn’t stop until I feel the mad gush (IYKYK) and the cramp/contraction is over. i know this sounds crazy, but because my bleeding is so heavy, i almost think the clots/lining clog up in my cervix?

Has anyone dealt with this before? It is literally the strangest thing and the cramps will not go away until I feel things passing. Sorry to be gross, but i have no idea what this could be. Endo? Polyps? Help me out!