What Causes Rashes On Vagina After Sex?

im 18 years old i hve a boyfriend who iv got tested with and he has no STD and i lost my virginty on the 8th of october we did use protection than it was too painful so we he took the condom out.on the 12 november my vagina started itching now on the 17 november its getting worse. im starting to get a rash the skin on my vigina is shrining up and its starting to hurt when i pee and the place where the pee comes out has white liquid/powered coming out. im really worried. i don't know my height bt i weight 60 somthing kg