How to treat acne overnughy?

You can start. You're not going to make your acne disappear overnight even in this era of quick-fixes. If you have only a week before the prom, get with your personal physician and perhaps a combination of a topical agent (i prefer benzoyl peroxide) and an antibiotic (topical or systemic) may make you look better. You're big enough to be caring for yourself long-term, day by day. Good luck.