A 2 year old unimmunized boy weighing 6 kg presented with fever, cough, and difficult breathing for 5 days. There was a history of fever with maculopapular rash lasting for 3 days around 7 days prior to this episode. The child is febrile, has a pulse rate 116/min, respiratory rate: 72/min, SpO2 88%. There is severe chest indrawing and nasal flaring. Auscultation revealed bronchial breath sounds on left side and bilateral crepitations.?