What Causes Dizziness And Vaginal Bleeding After Having Unprotected Sex?

I had unprotected sex last Fri. Since then I ve been feeling rather sick. But today was the worst day today I felt very faint dizzy and shakey and was nearly sick. Since about 12 o clock today I started bleeding at first it was very light then got slightly more heavy no clots then light again now its starting to get a little heavier but nothing like Norma and also its a week early!