Bleeding when not on my period?

Okay so I am 15, I lost my virginity this year during may (spring break) and I have had sex 4 times since the most recent was today and it hurt more than it did all the other times (it was withh the same guy) but i got home and I waz kind of bleeding I think, not quite blood but like weird brown red bloody-ish, kinda thick, but I googled it and it could be a multitude of things but I am worried It is like an infection!

Any ideas what it could be?

If so how to treat?

Could I have sex again soon do you think?

Oh and my eve calendar says my period is gonna be in like 11 days and my last period it was doing a similar thing 10 days until I actually got my period