Whenever HCG levels drop, it is a sign of a miscarriage. That fact that you went from 391 to 100 something is a significant drop. And with te bleeding included; I'm sorry to say that you are having a miscarriage.
hello monica, i'm really sorry your dr's havnt talked to you or explained that it very much looks like you have had an early miscarriage. The same happened to me at 6 weeks, i had been bleeding, had my bloods done but for me my levels were still rising 187 i think, but 3 days later i had an ultrasound and there was nothing there, no sac i had miscarried. its very hard and i still feel numb, this was 3 weeks ago. Please go back to your dr and let them do bloods again to be sure. take care and best wishesxx melissa