HCG level fluctuations

Michele

Does anyone have any insight? I miscarried on 1/15 at 5 weeks. On ultrasound no gestational sac seen, bleeding and cramping for 12hrs. HCG 2400, on 1/17 HCG 1690. Follow up HCG 1/24 3895, ultrasound showed gestational sac, no yoke or fetal pole seen yet. I see MFM in 14 days. I have a terrible headache and nausea today. What are the chances I’m actually going to have a viable pregnancy?