I had this problem until I was 19. I couldn't retract the skin because it was so painful. I had a very short frenulum so I couldn't even masturbate. I went to a doctor, he said I should circumcise. DO NOT circumcise your skin. There's a much simpler operation where you just cut and remove the frenulum. I learned this from Google, the operation lasted 15 minutes and my recovery was extremely fast