chances of me being pregnant?

Amy

my last period started on the 3rd of april and ended on the 8th but it was weird because this period came 2 weeks early which never happens. I had unprotected sex on the 10th for about 15-30 seconds max before i made him wear a condom (i’m not on the pill) which i know is stupid because i’m aware that precum can get you pregnant, but i don’t even know if he had any. Both of us have been tested for sti and we are clear. For the past 3 days ish ive been seeing this weird brown discharge when i wipe after the toilet occasionally with slight cramps but no period and i’m worried that this could be implantation bleeding. However about 1 week ago i stopped taking antibiotics that i had been on since january so maybe this could be linked?? i am going to take a pregnancy test on the day of my missed period to be sure but does this sound like pregnancy or am i overthinking it?