In the past I have had a tendency to develop yeast infections in my legpits, this a side effect of taking antibiotics. I essentially eliminated the yeast infections in the past 3 years by drying myself carefully after every shower (I use blow dryer with heat on entire pubic and anal regions), and applying Zeabsorb anti-fungal powder. A few times in the past couple years I felt a twinge of itching and observed a flash of red patch in the legpit. Zeabsorb applied for a few days knocked it right out.
For an active yeast infection, NEVER take any zinc oxide ointment. It will lock in moisture - there is water in the ointment that feeds and nourishes the yeast infection. For an active yeast infection only use powder, drying agents and oral anti-fungal pills, and try to go off antibiotics if possible and until yeast infection is under control.
I have successfully battled a few major ones and a bunch of small ones. Most important thing is personal hygiene in keeping the prone areas dry. If you do this, you will preempt most yeast infections.