Because I have Googled and it's a bit scary
Twice I have experienced a discharge after sex which has contained a very faint smear of blood (not even enough to cause spotting)
But my menstrual cycle is all over the place, I've no idea if I'm due on. Have also had unprotected sex... vague notion that I ovulated at the weekend (because of changes to CM) but wouldn't that be too early for an implantation bleed?
I need to go to the GP don't I?