Q. A 4-year-old boy presents to the emergency department with a sudden onset of coughing and choking. His mother reports that he has been coughing intermittently for the past hour and is now having difficulty breathing. On physical examination, he appears anxious and has inspiratory stridor. Vital signs are as follows: temperature 98.2°F (36.8°C), blood pressure 90/60 mmHg, heart rate 120 beats/min, respiratory rate 30 breaths/min, and oxygen saturation 92% on room air. The chest X-ray reveals hyperinflation of the left lung. What is the most likely diagnosis for this patient's symptoms?