Hi So Like Tuesday I Had Unprotected Sex Now Today

Hi so like Tuesday i had unprotected sex now today is Monday and i just started getting these really strong urges like i have to pee and when i go to use The bathroom its a light red like blood and its not a lot of pee just a little and it comes out really fast and out hurts as if the pee had been sitting in me forever and was finally coming out. What is wrong with me?