Really confused

So I had unprotected sex with my boyfriend more then a few times after my period but then I missed a couple of my birth control pills and the bleeding started really light at first but it started getting heavier but I’ve been having the pains in my lower stomach but they don’t feel like period pains but I’m really confused as to what it could be because I’ve missed my pill once before for a couple of days but it didn’t feel like this. Can someone tell me what it is?