I am 23 yo, 186 lbs, 5'2'', and have no serious medical issues. I do have PCOS. My last menstrual cycle ended on 3/30. On 4/10/13 I noticed a was bleeding a little, then as the day progressed it was a lot. It started out pink, was heavy red, then brown. By noon the next day it had completely stopped. What could cause that? I did have intercourse the night before if that may be relevant.