What Causes Swollen And Itchy Labia Minora?

Hi, I am a 21 year old woman who has had swelling in the area between my left labia majora and minora. it has settled down some in the area between the two, but now my left labia minora is swollen and is very itchy. what do you think this may be? its causing me to crack down there because i keep itching and scratching.