This my work for you or not but it's what helped me the most heal my bacne.

1. Wash your back in the shower with penoxyl 10% benzoyl peroxide bar soap.

2. After you back has dried apply tea tree oil (use tea tree oil am and pm)

3. Take vitamin D3 (one a day as bottle directions said).

Tips: wash your sheets often, where clean shirts/tank tops, when you go to bed (if you where clothes) make sure they don't get you too hot it's best to stay cool because your back may absorb your sweat and cause a pimple.

My experience: I would say that my bacne was mild-moderate, needless to say I felt embarrassed to where a swim suit or tank top. It took a week or so to notice a difference but that's what worked for me. Good luck!