How do I get rid of dark spots on my legs?

I have dark spots... they are kinda like blackish. They were caused by eczema. I have it on both of my knees and the back of legs.. I also have some on my elbows and the back of my thighs. I went to a dermatologist but it never really helps. I want it go to away really fast so I can start wearing shorts and t shirts again. ): Its also dry around my legs and arms. The black spots aren't going away, its been years... I just need it to go away quick. I'm so insecure about my legs.. everyday I wish I had perfect legs like all my friends do.