I have acne on my back and my chest. is there anything i can do to stop it?

Yes: Unless you are a lady who can take the oral contraceptive pill, this will almost certainly require a systemic antibiotic, plus some topical rx. If this fails, a dermatologist can give accutane, which is unpleasant, somewhat dangerous, and extremely effective. Being young is rough enough without having a treatable disease neglected. Good luck.