Sudden Burning

me and my boyfriend were making out and getting heated and he was on top of me and kind of dry humping me and then when he would push into me it hurt, i thought it was because of my tampon and so we were gonna go have sex and I went to the bathroom but the left side of clit or labia was burning and red. what could this be? it's burning right now and i peed a little and it burned as well ):