Possible miscarriage?

Alexandra

I was in the hospital last week with bleeding that only lasted 10 minutes. They dated me at 4w5d but could only see a sac and yolk sac no baby. I had my ultrasound yesterday and she said I was 5w5d and we saw the heartbeat. Problem is my blood work came back and my levels dropped by 1000 in a week and my thyroid was high. Is this a sign of an impending miscarriage?