Brown sticky discharge and cramps

Hi guys. So I’ve been feeling cramps come and go today and before dinner i noticed i have brown discharge. I haven’t had my period in like 3 weeks. I’m currently on the pill and have been since August of 2020. There was a period in December were i had a cold and was taking mucinex for a week and a half. Once i felt better i had unprotected sex. I’ve taken two pregnancy tests a couple of weeks ago and it came out negative. Should i be stressed? Or could this just be my period coming?