Birth Control and Bleeding Heavily

Can someone tell me wth is going on? I just started birth control about a month ago and I’m 3 days away from the placebo pill. Two Fridays ago I started spotting which I was told was normal. I’ve been spotting ever since and the bleeding has increased to a super heavy period. I’m having huge clots and cramps. I also had sex for the first time the next day after the spotting started but I didn’t bleed. I don’t know why I’m bleeding so much when I’m not even on the placebo pill and I’m super worried. Also there was a really huge blood clot with clear stuff in it in my pad today.