What Causes Pain And Burning Sensation In Skin Around Vagina?

Hi...i hope u can help me.... after i had sex i didnt have a pad so i used toliet paper as a pad.... then later when i was goin to shower i felt discomfort down there. As i showered the pain got worse and now when i pee it burns the skin on the outside and it causes it to swell .... its very sentative to touch.... i have no discharge or any other problems. Just right there the entrance to my vagina....plz help me.