A 17-yeаr-оld previоusly heаlthy mаle presents tо the emergency department with persistent fever, worsening sore throat, and right-sided neck pain. Ten days ago, he was diagnosed with viral pharyngitis and discharged with supportive care. Over the past 48 hours, he has developed pleuritic chest pain and shortness of breath. On examination, he is febrile to 39.5°C (103.1°F) and has tenderness and swelling along the right sternocleidomastoid muscle. Laboratory studies demonstrate leukocytosis and elevated inflammatory markers. A chest radiograph reveals multiple bilateral nodular infiltrates. Which of the following is the most appropriate next diagnostic step?