Bleeding from vagina

i have no idea what to do. around 2-3 days ago i had sex with my boyfriend and straight after we finished i started bleeding heavily all over the floor from my vagina. i know it’s not my period because it finished 2 weeks ago. it’s been constant bleeding and pain and today it’s gotten much heavier. i know i should go to the doctor, but does anyone have any ideas on what it could be?