need some advice!!!

So I'm currently 6 weeks pregnant and my hcg levels are above a 8000. I had experienced some heavy bleeding and some serious cramping and pain in my lower back. Went to the emergency room since it was late and my O/Bs office was closed and they still see the told sack but no heartbeat. Also I have some uterine hemorrhaging. I have to follow up with the OB on Monday. My concern is that there is no heartbeat at 6 weeks. Anyone else experience anything similar?