My sister had severe acne her entire high school career and still has it (she is 26). I thought I dodged the bullet but got acne for the first time at the end of my senior year of college. I broke out horribly and it took almost a year to get it under control.
Step #1 See a dermatologist
Step #2 Ask doctor about a similar protocol as I follow:
* Wash face twice a day (definitely after exercising, ideally in the morning and evening)
* Apply clindamycin/benzoyl peroxide (Benzaclin, Duac) in the morning
* Apply retinoid (Differin) in the evening with good moisturizer
Step #3 Consider seeing an allergist or immunologist if acne persists
Really oily skin runs in my family so consider my protocol with caution. Hopefully she doesn't have cystic acne. That's purely hormonal and is a b*tch to get rid of (typically only option is accutane and/or laser therapy).
God speed young blood.