I have been using Retin-a micro for almost a year but about a month ago my dermatologist gave me a higher strength (I was using 0.25% and now I am using 0.8%). I have a lot of blackheads on and around my nose, and some one my cheeks. Has retin-a micro, or tretinoin rid you of your blackheads? Or at least helped some of them go away? Please someone help me!