i need help i wanna know what’s causing this

Hi so i’ve been having sex for the past 3 days and last night i had it again. well this morning i went pee and when i wiped i had blood. i got off my period last week btw. i don’t understand if he hurt me or something i’m kind of sore down there. Well i just went again and when i wiped there was blood AGAIN but there is no blood on my underwear. What do you think is the cause of this?