Scared: brown discharge and cramps

Jessica
I'm about 6w4d and two days ago I had a pinkish color to my discharge, then yesterday it was a light brown, now today it's a dark brown and is a bit heavier. I now have period like cramps.. This discharge and cramping usually happens when I'm about to get my period... But how is that possible when I'm 6 weeks pregnant. Should I be worried?