What Causes Swelling In Labia Minora And Itching?

My labia minora is swollen on the right side. I was very itchy and irritatd this morning so I was scratching and pulling at it, likely due to yeast. After I treated it with plain yogurt and cleaned myself up, I notices the one labia was swollen like a big sac. I rested for two hours with no ungarments touching but the swelling has not gone down. I am a 36 year old woman in good health. i'm 5'3" and weigh 150 pounds.