help me

my boyfriend stuck it in no condom for maybe 6 seconds. i went to the gynecologist and they did a routine check up and said everything was good (negative tests). i am 2 days late which is normal for me. and i have been cramping and today i saw a very little amount of bright red blood on the toilet paper. my boyfriend says i’m okay and that everything is okay..

is this just a sign of an on coming period?