I am a 26yr old female. For about a week my breast have been really sore andI finally got my period Sunday evening, I was cramping so bad I felt like I was in labor. The next day, Monday, I was so light I only needed a panty liner and that night I had no flow and only saw light pink when I wiped after going to the bathroom. The same thing Tuesday and Wednesday, I only saw pink when I wiped after using the bathroom. Wednesday afternoon I had some cramping. Thursday there is nothing no pink discharge and no pink when I wiped. I've had the Meraina IUD removed last year June 2010 and I've had normal 3-5 days menstrual cycle ever since then. What could be causing this?