Bfp, now bleeding

So I got bfp last week 3 days before AF. AF was due Friday but never came, Monday I started bleeding lightly but kept testing to make sure it was still there and up until Tuesday I kept getting positives. This morning (Wednesday) there was no line. I’m still bleeding but not enough to fill a tampon after a few hours. Went to doctor waiting on blood work but just curious if this has happened to anyone?

I’m thinking it’s a chemical but praying for the best!