Progesterone levels/Heartbeat

I'm currently 6w4d with our rainbow after a 37 week loss. I went to Dr Thursday (6w0d) because I noticed barely noticeable light brown discharge (like, I think a normal person wouldn't have noticed, but because I'm so in sync I did 😅) im sorry it's TMI. Went and did ultrasound. Yolk sack was .63 cm. No heartbeat. Did blood work. HCG was 8000+, progesterone was 16. Doctor was concerned with no heartbeat at that HCG levels, and that progesterone was not over 20. Put me on 100 mg progesterone twice a day and have repeat ultrasound on Tuesday. This only happened Thursday and I haven't had it since. Anyone experience with this?