Brown/reddish discharge for 2 weeks?

Hi! Recently i’ve been experiencing weird brown/thin discharge. I am on birth control. As the timeline goes, Wed. Jul 7 i was blood tested and there were no signs of a pregnancy. Thursday is when I had sex. The following week, i missed Monday’s pill so i took Tuesday’s and Monday’s together. Wednesday was when I started spotting red and brown and it has not stopped. Currently, I have been experiencing PMS since I have stopped taking my pills for my period week but I have had very little blood come out. I’m kind of freaking out because I don’t think i’m pregnant, but i’m testing tomorrow. My last period was June 27-30!! Any advice would be great 🥲