Acne: Differin Gel 0.1% and Clindamycin Phosphate Lotion, WILL THIS WORK?

Dermatologist prescribed it for my skin which has a little acne....will it work? I am 16 yr old girl, and the differin alone, after 12 weeks still just made it WORSE and not at all better....so the derm. said to try the differin at night and once it dries apply the Clindamycin Lotion and in the morning after washing face apply the Clindamycin Lotion....anyone tried this?