I am 32 years old and have always had a 28 day cycle since i could remember and even after my first child who is now 7. Regardless of stress levels it always came on time . My last menstrual was July 13th 2013 last for 5 days. I recently went to the E.R for a bad headache on Aug 6 and the dr asked if i had been under any stress i said kinda but nothing to the extreme. She took a pregnancy test it came up negative. My Menstrual was suppose to come on Aug 10 and i am late. My partner and i had sex Yesterday on the 11th and all of a sudden today Aug 12th 2013 i felt a sharp pain in my lower abdominal area followed with light back pains and heavy brown menstrual bleeding but now the pain is gone. it is flowing light. Before i have a menstrual i can tell when it is about to come on. By me missing my period i was scared. Now that this bleeding has occurred i don't know to think. Is this normal in pregnancy or can this be just my period coming on late.