The lips do not have oil or sweat glands, and their moisture content comes from saliva and is directly related to how well hydrated you are. Make sure that you are drinking enough water...half your body weight in ounces per day...and continue using a natural lip balm for protection. Dr. Hauschka makes an excellent lip care stick or balm...available at most health food stores.
This is not an STD...stop worrying! Stressing out about this may be making your body more acidic which could be contributing to the problem...RELAX!!!