bleeding

so i have been bleeding for about 3 days now, it started super light orange, turned brown, & now has moved to red.

i went to the er yesterday because i assumed i was having a miscarriage, but the ultrasound showed baby was fine, measuring 5 weeks & 6 days with a heartbeat of 111. after i got home from the er is when the bleeding picked up and turned to red.

she said she couldn’t really see any cause for the bleeding, i am 5 months pp, so this was an unexpected pregnancy but im still heartbroken worried im going to miscarry.

does anyone know what could possibly cause the bleeding if the baby had a heartbeat?

also is it possible to start miscarrying while the baby is still alive?

i was so relieved yesterday that the baby was okay, until i got home and the bleeding has turned red. has anyone had similar experiences?