Possible miscarriage 😢😢😢

I had a horrible migraine last Wednesday that lasted for 2 days then Thursday night I had light pink spotting. Friday and Saturday no spotting but left cramping and back pain. I had levels hcg levels drawn on Saturday. Today no cramping or spotting when I woke up but a light head ache I get to work and I felt the gush come out I ran to the bathroom and bright red blood. I went to the ER and had an ultrasound and they said there is a yoke sac and a fetal pole but no heart rate. There shout be one at 5 weeks and 6 days right?
My hcg levels went from 4000 to 3500... they are going down.

So now my hcg levels are coming up they are now 16000. Still bleeding bright red no clots... I am getting an ultrasound on Friday..what is going on? Has anyone had this happen to them.