my last period was July 24. i missed my period in Aug. it is now a week before my next period is to start. on tuesday, 9/9, i started light cramping in my lower abdomen and brown spotting only when i wiped. on wednesday, 9/10, the cramps got a little worse and the spotting became dark brown and a little more than the day before. today, 9/11, its like a period but dark and heavy. before, i was always regular with my period, always on time, only 3 days, no cramping, no PMS. i just turned 37. what is really going on/