I have an itching problem that isn't a yeast infection..Help?

The inside of my vagina, like flaps and hole, is itchy mainly at night. I went to the gyno a few months ago and my yeast cultures came back negative. I'm supposed to go again in about two months. I have sex about twice a week and we use latex condoms. If I was allergic to latex, the itching would go away after showering and time in general right? Also, I shave so it isn't crabs or anything.. And there aren't any bumps or weird discharge.. Its annoying. Any ideas what it might be? I'm 19