Hello, I took plan b aug 19, 20 hours after I had protected sex with my boyfriend, ( took precautions over pre cum) i didn't have any effects , and got my "period" a day after my period was supposed to come (sept 13) It started light then a bit heavier, lasted 5 days, about 28 days after I had bleeding (OCT 7) and it was light medium and then until the 9th I had bleeding , but between 8and 9 it was lighter then a bit heavier; now I have usually 4 day lengths during my period but I haven't bled so far.. I'm having bad back cramps where my kidneys should be; like my lower back, my stomach hurts as well, on the middle upper left side; I did take a pregnancy when i was waiting for my period (sept 13) and I tested negative, so now I'm scared that I may be pregnant ? Or why did my period or bleeding come so early? Like about 2 weeks earlier..I really want to know..I'm very scared and I don't know what to do..so please tell me what you think. Or what I should do.. --also my boyfriend and I had protected sex sept 20, no semen was ever near me and before he came he pulled out.