D&C question

I had a D&C a little over 5 weeks ago and no period yet... Well exactly 2 weeks after d&c I was bleeding and it was just as heavy as my normal period. But I had an ultrasound done and doc said it was to early for it to be my period I guess he was looking at my lining on the ultrasound. SO the question is what exactly was that heavy bleeding that resembled my period??