sore vagina

i’m kind of freaking out. me and my boyfriend had sex for the first time last wednesday. we were protected and everything and he hasn’t been with anyone in months. yesterday(monday) i started feeling sore down there. kind of like i had fallen and hit right between my legs but not that bad. it’s just uncomfortable and really annoying. almost like it’s bruised. sometimes sitting down for long periods of time makes it worse. when i showered today it went away but later on came back. i don’t know what is wrong with me. any help would be greatly appreciated. i have no idea what’s going on