Bleeding during Sex

So my boyfriend and I had sex about a week ago and had to stop because I started to bleeding, I am not due for my period for another 11 days or so. We tried having sex again tonight and as soon as we started we had to stop because I started bleeding again. It stops about an hour or so afterwards and it doesn't show on my underwear. These are the only times I've bleed and it not be my period. Do you guys know why? I currently am not able to afford insurance so I'm trying to avoid going to the doctor unless I have to. I just don't know why?