i had unprotective sex about 3 weeks ago and i started to spot the 31st and i wasn't supposed to start my period til the 10th. i spotted dark brown for four days then yesterday i started to have a little blood mixed into it, and today ive had nothing but light bright red blood. i have never had this before, my periods are usually always on time and heavy, i took 2 pregnancy tests and both were negative. what do i do? its day five and i have no idea what this is or what to do.