A 2-year-old girl from Delhi is brought to the clinic with a 6-week history of weight loss, recurrent respiratory infections, and chronic diarrhea. Weight is 9 kg (expected 13 kg), height 82 cm (expected 89 cm), with no edema. Triceps skinfold thickness is 6 mm (normal 12 mm). Hemoglobin is 9.2 g/dL, and serum albumin is 2.8 g/dL. The child is alert and feeding orally. What is the most appropriate next step?