i need help!

i had sex with my boyfriend on june 15 first we didn’t use a condom but later that night we did. almost two days later i took plan b. today (june 23) i noticed brown discharge and later i had bleed once and that’s it. i took a pregnancy test so i know i’m not pregnant but the first day of my last period was june 5. im having a lot of cramps which i usually don’t have and i’m not bleeding just having brown discharge and when i went to the bathroom to pee i wiped and saw clots of blood. can someone please tell me what’s happening