awful burning sensation after sex! 😩

Kara
So it doesn't happen every time, but probably 75% of the time my boyfriend and I have sex, it burns almost immediately afterwards. It doesn't bother me at all while we're in the middle of it, but about 2-3 minutes after, the inside of my vagina feels like it's on fire and I have to sit with a cold wet wash cloth on it.
 We don't use condoms or lubes (I'm always plenty lubricated though, if ya know what I mean), I don't use scented soaps, he doesn't cum inside of me, and we aren't unusually rough during sex. I've even been tested for STDs. I can't for the life of me figure out what's wrong with my vagina! 😡