What can I do to get rid of these scars/dark marks from recurrent acne/abscesses on my inner thighs and buttocks? (Photo)

I’m left with these scars/dark marks from acne/abscesses. I’ve had abscesses as big as 2 cherries on my inner thighs, buttocks, legs, underarms and back but I have not had one for 3 months now since I’ve changed my diet. How can I get rid of these dark marks? And how long will it take for them to be completely gone? I would greatly appreciate any advice.