Help Me Understand Pls!!!!

I had a positive pregnancy test on July 18. My af was 7 days early and it came the day after the pregnancy test. Af was really light and then on the third day I passed a really big clot. That was not normal at all. Once the clot passed the bleeding stopped 3 days later and I still had the cramping. But in the mix of all of the now all the pregnancy test are coming back negative. After getting a positive I went to the doctor. They didn’t do any blood work after I told them I got a positive pregnancy test. They only took my urine.