What Causes Burning Sensation On Vulva And Swelling On Labia Minora?

My vulva burns.There is no itching or discharge.now my labia minora is swollen and hard.I've been prescribed anti fungal cream and pills for what my doctor thought was Bacterial vaginosis.I had a pap test done last week and it came back negative.I want to know what it could possibly be.The burning started on my right labia.It was a throbbing burning pain with no redness,discharge or irritation.Now it seems to be all over and my labia minora is hard and enlarged but it doesn't hurt.please help.