I got my period May 11,2014 and three weeks later June1 I started to have light pink discharge and mild cramping, it was way to early to start my period. I wasn't bleeding enough to use pads but on the third and last day I passed a small blood clot. Then two weeks after that today June 19, I started my period. This has never happened. Should I be concerned? And why does this happen?

Every so often you'll get break through bleeding mid cycle. It is perfectly normal to be honest. Nothing to be worried about. Why does this happen? So many reasons that include because the sky is blue and the grass is green.