Bleeding

I am 5wks today. Yesterday I had some extremely mild cramping, nothing serious and they would go away within 5-10 mins. Along with that I had light bleeding. Not spotting but not period bleeding. It went on all day but I didn't fill pads and now everything subsided and I feel fine except for being extremely tired. What could that have been? I should mention that I also have sickle cell disease and I am anemic.