well there r several possibilities, firstly it cud indeed be an early period, lots of physical activity can bring it on early. it depends, r ur periods usually heavier than this or not? cuz iv its the same as wat u normally have this cud be it. on the other hand maybe the vast amounts of sex have caused u to get a bit sore, this can cause slight bleeding. then again, if it is cuz ur pregnant, the best thing to do is take a test after the time u wud normally expect ur period, or even better, go to the doctors! best to get it checked out really!!! good luck!!!! xx