First, I totally stopped touching my back, popping pimples, etc.
Wash sheets and towels once per week
Never wear a shirt or bra twice (I know, it's a lot of laundry)
Shower immediately after sweating
Shower EVERY NIGHT
Lather back with tea tree oil soap (you can buy it at whole foods and other grocery stores)
Rinse with cold water
Pat dry and lightly rub some white wine vinegar or rice wine vinegar all over your back with a cotton ball. Let dry
Using a Qtip, put Tea Tree Oil on all the pimples. Let Dry. Wear a loose and clean shirt to bed.