I had a at home pregnancy test it came back positive then I had a test at the emergency room it was positive then I took a third one it was negative I have been bleeding both positive and the last negative

Dear do not worry may be the stick was expired or used so next time go to doctor or lab.

The test may have been wrong. But you could have miscarried too.

You are pregnant if you get a positive, a false positive is rare,

Most likely the negative one was taken latter in the day or was a bad test.

Time to go to the doctor and confirm with blood test