Has anyone used Clindamycin gel long-term, more than a year, with success? I've been using it for a month and I LOVE what it's doing for my skin but I heard that there are high incidences of resistance after a few months. I hate for that to happen. What's the point of derms prescribing it in the first place if it can't be used for long-term because the skin becomes resistant to it? ???