What Causes Itchiness And Swelling In Vaginal Lips?

Hi I have been having some itchiness on my vaginal lips. There used to be an open sore because I itched it so hard. The next few days the sore went away but the itchiness has returned. Tree are no bumps or blisters. The pain is very mild and there is no pain during urination or wiping. The area that has been itchy is slightly swollen but has not gotten larger in size. Please help