BROWN DISCHARGE MEANING PREGNANT?! Please help

Please help me. I had sex almost three weeks ago. We used protection, he didn’t edjaculate at all, and I took plan b four days after. My boobs started aching a little two days ago and hasn’t gone away since. Now I think I see a slightly brown discharge coming out of me. I heard spotting is like a brown discharge and spotting could be a sign of pregnancy. Can someone please help me. Could this just be side effects of plan b? I heard side effects should come right after taking the pill and only lasts about 24 hours. Or....Could I be pregnant????

My discharge looks something like this right now. I read that implantation bleeding happens around day 22-25 of your cycle. And early signs of menstruation occurs on day 26-27. Today is day 26 for me so this could be my period coming but like I said I took plan b so it messes up my cycle. Someone please help me :(

Update 3 days later:

It was my period! I got it! Thank you all who gave me advice!