hi, i m 26 years old, for the past 4 years I ve been suffering acne, my dermatologist prescribed me tretinoin cream and it didn t cured my acne, then after that he gave me clindamycin it has no effect until now I ve been suffering. i m using now benzac gel, at first it gave me an amazing effect but now I still having troble with some zits. what do I need to do? thank you