Weird pregnancy tests!! Now Bleeding

As the titlte states, I had my first positive pregnancy test at 6dpo. The next day it was negative. 8 dpo I had another positive! I was so weirded out I took another test at 9dpo. BFN. I tested 2x a day from then, all negative!! Until today. I started getting dark brown old tissue at like 4am. At 7:30am i took a test and got a BFP! Today would be 13dpo. I put a tampon in to see the results when i woke up from my nap. I just woke up and more old dark brown tissue in addition to rusty red blood. I'm so confused. Is this a chemical pregnancy?