Strange light-colored blotches on private areas

Hi, I am a 16 year old male and I have a problem with my penis. I know my penis is supposed to be a darker color than my regular skin, but there is something wrong. I have light skin blotches on the top-side of my penis shaft. I also have it on the under-side of my shaft and my sack. The blotches are the same color of my sack. My whole sack is this color but my sack looks normal with the light color, but my penis doesn't. I don't know if my whole penis will change to the same light color or not. Should I be worried? How do I know if it isn't a skin disease? I also have it on the inside of my anus, right in the crack. The strange light color is also on my gooch (the part between my legs that goes from my crack to the bottom of my sack). Is this normal? Will it go away by itself? I think it gets bigger very slowly. The blotches appeared about 6 months ago. I am very self-conscious about this and I need help.