What Causes Discomfort Around The Genital Area?

For a little while I have noticed that I have had some discomfort around my genital area, just a small amount of discomfort on the outside lips of the vagina. Upon further inspection I have noticed what looks like a single blister on them. Somewhat like when one gets a cold sore. I do shave the are, so I thought it may be a hair, however it does not appear to be that. This has made me quite concerned because I am not, and have never been sexually active. I Like to think myself as hygienic and I am a very clean person. I have however, been under a lot of stress, and have started to take public transportation, while walking quite far in the heat. Witch, in turn makes me sweat quite a bit, along with my uniform being extremely hot. But I always clean myself. So the appearance of this sore is making me very concerned. Help would be highly appreciated.