I'm 17 years old and my periods have NEVER been regular, but I've started back having sex recently. A few months ago I had unprotected sex and I did this weekend too. But the guy didn't "release" inside of me. But the day after I have sex, my period, I guess you would call it comes on. It came on yesterday, and it was almost black. It wasn't much and it's still doing the same thing now. I'm hoping it's just old blood, but it's been about a month and a half since my last period and it lasted over a week. Does anyone have anything that would be helpful to me??