Discoloration and stretch marks on upper thighs?

ok, so, on my upper thighs, lower back, and my well, butt, my skin is really dark and i have some stretch marks. This is really embarrasing, what can I do about the discoloration? My mother thinks its because of my black skinny jeans. Is this true? Cause I am a jeans girl and black is my favorite. I was thinking of buying cocoa butter from palmers, will that help?