Really bleeding in early pregnancy

Hi all! So just trying to see how common this is. Last Friday at 5 weeks and 2 days I started lightly bleeding light brown. With my history or MC I went to ER and they saw a sac and yolk sac and said all looked well and to take it easy. Well the bleeding got a tad heavier and more pink and more cramps so went into dr

Tuesday and saw baby with a heartbeat and couldn’t find any issues. Anyways fast forward to Wednesday night into this morning I woke up to horrific cramps I mean like early labor cramps and a lot of bright red blood that did cover my underwear and kept coming. Also had some clots. Dr did sono and low and behold still a baby with an even better heart rate. She saw all the blood on the sono wand but couldn’t find anything wrong. No hematoma or hemorrhage- nothing. The only thing they came up with is maybe “vanishing twin” or “some women just bleed in first trimester” now I’ve had 4 live births and never bled a drop. Soooo how common is this really? Bc I’m not spotting it’s like a full on period or miscarriage. Iam beyond baffled 🤪 and it’s driving me nutty