Hi and welcome. If you have never had sex then this would not be std related. These bumps could be natural to your body and your just noticing them for the first time. You feel these are not natural you might have picked a a fungus from not washing your hands as you do masturbate a lot. With the excess skin, your still young and growing. Give yourself a few more years about the skin issue you might grow into it.
If your concerned about the rash it would be best to have a good check up with your doctor to make sure the growing boy in on the right track.