Okay, so I'm naturally olive in skin color and have always been like that, and tan horrendously in the summer but in the winter I would always get right back to my normal color. 
So now, years later my skin has suffered from my lack of sunscreen and exfoliation and I want to obtain that beautiful skin color back. 

My feet and ankles (where my shoes and ankles cover) are my natural skin color, also Kind Of my inner arms ¬†because they were covered all the time. But the rest of my body that have met the sun are not. But that's not what I'm worried about, because I know I could get those back to my natural skin color. My problem is that the back of my upper thighs and up (my derriŤre and back) are about 4-5 shades darker (than my natural color) including my abdomen.¬†
I want to know what is causing my skin to be like this! And  how to reverse it!
P.S. It's not spots, it's the whole thing (back, derriŤre and stomach and sides of those)
Why me!!