can't get a positive pregnancy test again?

I took 6 tests on Thursday and they all came back positive, I took one yesterday and Vvvvvvvvvvf but positive. Today AF is supposed to show up, I felt discharge and I freaked out so I went inside my car to check what it was and it was brown discharge. I freaked out and left work, I called the nurse and they really didn't say anything !!  Nothing! Just that is be receiving a call from my obygn in the next 48 hours or an office appointment. So I'm sitting here crying my ass off because I'm scared, I decided to take 2 other pregnancy tests right now and they're  showing negative !! What's going on?? 😭😭😭