You have a patient who is a positive for strep on rapid antigen testing (rapid strep test). you order amoxacillin after checking for drug allergies (patient is negative) but he returns 3 days later, reporting that his temperature has gone up, not down (101.5 f in office). you also note significant adenopathy, most notably in the posterior and anterior cervical chains, some hepatomegaly, and a diffuse rash. you decide: