Spotting at 5 weeks, no heartbeat. Has anyone seen similar

I got an ultrasound at 4 wks (high risk) and md was able to see a sac. My HCG levels were high- started at 2500, doubled to 5k in 48 hrs. I have been experience brown spotting all this week (my 5th week) and last night I saw some red (5 wks 3 days). I went to the ER and they did an ultrasound and drew blood. My HCG was at 28,000 but the MD said it should be closer to 40k if it were to be doubling appropriately since last week’s visit. The ultrasound showed a sac, yolk, fetal pole etc but no heartbeat. I have no cramps, I’m not consistently bleeding but I’m still spotting. Next appt isn’t till Tuesday. Anyone have something similar happen to them? Thank you for any input ❤️