Bleeding a lot after sex

Hey, so I have a copper IUD. Typically during sex it doesn’t get in the way, however sometimes if the angle changes just a little bit I get this really sharp pain. Last night, I was having sex and we weren’t doing anything weird or different. But he just moved a little bit and it hurt real bad and after sex I started bleeding a lot. Has this happen to anyone? I can still feel the strings, but I am a little worried. It’s been like 12 hours and the bleeding has stopped but my vagina still hurts.