I usually have normal periods, but this one has been very different. Last month it was normal but short ( 6-11 to 6-13)and a little lighter than normal. this month it came a few days later than i expected ( 7-15) and its only a littke brown discharge when i wipe. i dont need more than a panty liner. the cramping has been alot worse and constant. it usually was just a little on the first few days. breasts tender and headache everyday. my boyfriend and i dont use any kind of birth control , just the pull out method. what could be going on?