How to get rid of pimples on my shoulders,chest,and back?

Ok so i have acne on my chest,shoulders, and back its mild but its got on my nerves so i went to the doctors and she perscribed some antibiotic and i dont think it has been working to well...so i have alredy tried my face wash on my chest and it dident work..so i dont know if i should keep using my medicine or to try something else?