Q - How do I stop bleeding every time I have sex?

So I had a lot of problems with birth control which resulted in horribly extended periods which would never end so I got an IUD so I wouldn't have to suffer as much. Since I got it I bleed every time I have sex, I got it removed about a month ago and haven't had sex since until last night when I did and I bled again. Why is this happening and how do I stop this?? Please help..