Acne is easily removed when vitamin A is added to the diet, usually about 50,000 to 80,000 units per day. This is a fat soluble vitamin so once the acne is gone, cut back to about 50,000 units a day and you should be fine.
As for dark pigmentation, it is known that dark circles under the eyes is a sign that this person doesn't have enough protein. Try adding a protein shake or two a day and if this is what it is, protein will take care of it.
Women should get about 60 grams of protein a day, men about 80, unless they are under stress, then it can go as high as 150 grams until the stress has passed.