You are probably feeling a little bit of discomfort on your penile skin. These rashes may be caused by irritants such as soaps, creams, or clothes rubbing against the skin. Since the rashes disappear within a few days and do not itch, then the chances are they are not the cause for alarm. To prevent rashes from recurring, you can try cleansing with mild, fragrance-free soaps and wipe the area down with a dry cloth. If rashes start to itch, hurt, or stay on the skin over time, it would be better to see a dermatologist.