bleeding after sex EVERY TIME

Every time i have sex i get my period. like full on heavy bleeding that lasts 3-4 days. i got off the iud and ever since i got off it, i bleed terribly after sex and i can’t get pregnant. no idea wtf is going on. it’s been 3 months now. i had my period nov 26-dec 3rd and then i had sex on the 8th and bled from the 9th to the 11th and had sex today and now i’m bleeding heavy again. no i don’t have any stds as i know it can be a sign. but i’ve been tested. no im not pregnant i took a test yesterday. so now im confused, can i not get pregnant from having sex today since i got my period AGAIN?