has anyone experienced this???

Day
Ok so I took a home pregnancy test on Tuesday of this week and got a positive. I went to the doctors Thursday and I took another pregnancy test there that also came out positive. I mentioned to the nurse that I was having some bleeding and cramping at this point. They sent me to the lab to get blood work done and schedules me to come back Monday afternoon. Earlier today my cramps seem to get slightly intensified and I was still bleeding so I went to er because my doctor couldn't see me. So now the hospital tells me that my pregnancy test is coming up negative. They weren't able to see anything on ultra sound and my hcg levels were 57. They said I am either miscarrying or I'm really early. I have to go back to er Sunday morning to have my blood checked I'm so nervous!!! Has anyone experienced this????