White spot on the penis. plz help

Hi im Tom , and im 17 , in about 6 month to a year ago i had a White spot on my penis, not on the head (glans) but on the shaft, it's the skin color changing to White (it's the same skin nothing changed its just the color), at first it Itch's but know it rarely does , and it's spreading vary slowly. i had been Masturbating with Lotion , does that Affect? I am afraid that it's vitiligo, is there another possibility?(it just on the shaft no were alse) plz i'm freaking out