i had a threatened miscarriage with my DS. I started spotting the day after my dating scan, went for another scan a week later due to the continued spotting then at 8 weeks had a sudden, large loss of blood. Went to the hospital where they said the blood was definitely coming from the womb but my cervix was still closed so that was a positive sign, although no guarantee. They sent me for another scan and at this one they did an internal scan and identified a subchronic haemotoma, kind of like a blood clot in the womb external to bub's sack and the bleeding I was experiencing was my body expelling the contents of that blood clot. I went on to have bleeding similar to the first day of af until I was 12 weeks pregnant when it just stopped and I went on to have a relatively normal pregnancy. Knowing what was causing it meant I didn't spend those 4 weeks completely freaked out, although I was still worried, just less than I was before I knew about the subchornic haemtoma. Until I experienced it I'd never even heard of it as a possibility but there are reasons for bleeding through pregnancy that aren't linked to miscarriage.
Hopefully you can get some information soon about what's happening.