My skin turned darker after getting acne treatment?

my face was really white. i had pimples couple of years ago.. I got treatment. i t worked however my facial skin color is darker than usual. my hands are white and face is dark and it looks wired... any comments.My skin turned darker after getting acne treatment?
maybe it had stuff in it to darken ur skin? :S i have the opposite problem, i have this small circle thats a rash on my left arm and my doctor gave me ointment with this stuff that makes ur skin whiter, now it doesnt blend in with my arm and it looks weird :(

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