A 4-year-old attends preschool three days per week. Her moth…

A 4-year-old attends preschool three days per week. Her mother reports she had a fever, runny nose, and muscle aches last week and was not able to attend school, but after the symptoms improved, a rash appeared. The patient is up to date on immunizations. On Exam, the NP notes scattered bright erythematous papules on the cheeks and chest. The NP makes a diagnosis of: