What Causes Painful And Sore Vagina, Post Intercourse?

I'm 19, my boyfriend and I have been dating for 3 months, we've had sex countleSs of time. And this kind of thing has never happened before. After engaging in sexual intercourse on saturday my vagina has been sore. We didn't do anything out of the ordinary, I'm not really shore what it could be, we're both puzzled. My vagina hurts like ever since Saturday, not really painful but I can feel it and it's uncomfortable. But is painful when you touch it and during sex. It hurts mostly on the right side. It kinda feels like it's swollen and a lump . Any ideas??