Bright red spotting

My boyfriend and i had sex this morning, it wasn't rough, but he stopped and said your bleeding. When i had checked it out, i was experiencing bright red vaginal discharge. I'm not on any birth control but i have never in the last five years of not using birth control had any scares, pregnancy symptoms, anything like that. I always have regular periods, usually 5-7 days. I have regular pap smears done. I had my period about two weeks ago and everything was normal. I don't have any cramping, no symptoms of pregnancy. I've also read that implantation bleeding is usually a brownish color, and mild cramping is experienced. I have no mild cramping, im not bloated.

Any time of answers as to why this is happening would be great.