Is this a miscarriage please help!

Yesterday I got my 5w6d ultrasound and everything looked great but heartbeat was a little low (80s-90s) but doctor said it was fine, and to come in in a week and a half. This morning I woke up and I was bleeding like a period, some clots but not much, and some cramping. I went to the ER, got my blood taken and Normal HCG results for pregnancy. Then they did an ultrasound and baby was in my uterus, heartbeat was 89. They told me to assume it will be a miscarriage, and offered me to take a pill or to go home and let it pass. I will be calling my OB on Tuesday to get another ultrasound, but I’m bleeding still just like a normal period with some clotting. Anyone have this happen to them? Please help!