Brown Spotting for 5 Days 😖😳😔

Hi ladies, I'm very confused and was wondering if any of you have had this issue before. AF was due around the 8/9th and I started spotting on the 6th which isn't tally unusual. That's generally how I know AF is on her way and I can stop taking my progesterone. So, I stopped the progesterone on the 6th due to the brown spotting, but AF still hasn't shown. I've never spotted this long. Usually, AF begins a day or two after stopping progesterone. I've taken hpts just in case but all were bfn. Any ideas? I have an appt with my dr on the 18th.