I am bleeding and i just had sex lastnight, i really do not think that it is my period because i know when they come. Could this be a sign of pregnancy? If someone could please help that would be greatly appreciated. I alsp have endometriosis and i do not think that, that is the problem either beacause i have never bled beacuse of that. i have never had a problem with bleeding this bad before after sex and for it to be a period it is too late.