An 18-month-old child with no previous medical history presents with a caregiver after 6 days of fever and dry cough. The child is up-to-date on all vaccinations and has never had any medical problems up to this point. Physical exam reveals a fever of 101.1°F, red dry lips, a strawberry tongue, cervical lymphadenopathy, a rash on the perineum, and erythema of the palms and feet. What is the next appropriate step? A. Antipyretics, antibiotics, and follow-up with pediatrician if otherwise well-appearing B. High-dose aspirin and IVIG C. Plasmapheresis D. Rapid strep test and LP; if negative, infection is likely viral and patient can be discharged