After intercourse II expierenced awful cramping. Why would that happen?

Fibroids or OTHER dx. 'uterus cramping' after intercourse may be due to several disease states: uterine fibroids (benign uterus muscle tumors) can cause painful sex (dyspareunia) or cramping. Also endometriosis may cause chronic or intermittent pelvic pain. Any inflammation of pelvic structures (bladder/bowel) may cause pain/cramping, too. If symptoms persist:time to see primary doctor/gyn. Hope you are better soon!