Help please?

So I’m extremely confused my hcg levels have gone from 37 three days ago to 5 today but I’m bleeding and an ultrasound was done and pelvic exam my cervix is closed, the pregnancy looks good and my gestation is right on track they aren’t understanding why my hcg went back down so I have to come back here in two days for a follow up has anyone had this happen and had a healthy baby? I’m so wildly confused and mentally drained.