Help please!

I found out i was pregnant Aug.23 took another test the 24th it came out positive.Then on the 27th got a proof of pregnancy but later that day i started bleeding. I went to the er on the 29th because i was still bleeding and they got a negative urine and blood test and there was nothing in the ultrasound they told me to come back in 48 hrs to check my hcg levels because they were at a 4. I went back an they dropped to a 2. I had no pains. I didnt stop bleeding till Sep.1st and i havnt had a period and ive been naesous and having headaches. I dont know whats goin on i have never had a miscarriage till now.