Blood in gestational sac?

3 weeks ago i found out having twins. Exciting!!!! Then twin B heartrate went from 118 to 86 and i was told to expect to lose that one. Last ultrasound 2 days ago showed no heartbeat for twin B. Next i was told that twin A had a great heartbeat at 147 but that there may be blood in the gestational sac. I get rescanned next week. I am heartbroken. Anyone have anything like this happen?