Same for me when I was on high doses of lithium (1200-1500mg). The acne came by cycles. I was fine for a while and then I would get it and so on. I was treated by a dermatologist and I was doing a lot better. A good advice she gave me: Not to put anything on my face. This means, no make-up, no night/anti-wrinkle cream and not even sunscreen, even if it says that it will not induce acne on the label.
Good luck.