A 6-year-old boy from Mumbai presents with a 3-day history of fever, sore throat, and a fine, sandpaper-like rash over his trunk and flexural surfaces. On examination, he has exudative pharyngitis, strawberry tongue, and circumoral pallor. Rapid antigen detection test (RADT) for Streptococcus pyogenes is positive. His mother reports he has had three episodes of streptococcal pharyngitis in the past 18 months. What is the most appropriate next step in management?