What Is The Swelling And Protrusion Of Labia?

my left side vagina inner lip is swollen and protruding it doesn't hurt but i am having a light discharge also, I have not been sexually active for 4 weeks. This happened one other time and lasted for about 2 weeks, afterwards the skin just kind of hung there and it was quite a while before the skin was normal again. Can you please tell me what is causing this.