Itchy vagina lips and clitoris?

About two days ago I began experiencing itchy vagina lips. Yesterday my clitoris began itching as well. What can I do about it? I seriously doubt that I have a std. I got a full std check at the end of April, and everything was fine. I think this may be because of a yeast infection though. When I have sex there is a white discharge, and sometimes I have vaginal itchyness. Has this happened to anyone before? I feel a little embarrassed, but I'm a female and things like this can happen.