How to get rid of the discoloration soon?

So I've got some- actually lotsa discoloration over my body like my knees and elbows, stomach,armpit, and under my butt and on my hips . I totally hate it. I am a black girl with a caramel skin tone then I have dark chocolate discoloration on the various parts of my body. Now imagine that, wouldn't it look odd to u. It is for me actually its very embarrassing especially when its summer time:( . Help ! maybe you guys could suggest me some natural remedies that would soon reduce the look of the discoloration. Oh and remedies for strecth marks too i'd really appreciate it. :)