Vagina Had Been Burning And Slightly Iching What Could It BE

My Vagina Has Felt Almost Swollen,Sore And Like a Burning Sensation Around It.Also It Somtimes Iches.Its The Skin Around The Vinga Opening That Is Hurting, But When Im Having Sex That The Only Part That Is Painful.If I Had A STI Woundnt The Inside Hurt? This Has Started 2 Occour Recently With A New Sexual Partner, Who I Have Unprotected Sex With.What Could It Be ?