21 yr old male really bad acne on the back and chest. What is the best thing to do?

Stop neglecting it. No home or over-the-counter remedy will clear you. Start using topical benzoyl peroxide and phone your physician for an appointment. You may get a sufficient response from a few months on a systemic antibiotic, or you may need isotretinoin. If you are offered this medication, which is not for the faint-hearted, please give it serious consideration -- most folks are very pleased afterwards.