A 18-month-old boy from rural Maharashtra is brought to the pediatric clinic with a 4-month history of poor weight gain, loose stools, and recurrent respiratory infections. On examination, he weighs 8 kg (expected 12 kg for age), has visible ribs, sparse hair, and mild hepatomegaly. Serum albumin is 2.1 g/dL (normal >3.5), and hemoglobin is 8.2 g/dL. He is alert and playful with no edema. What is the most appropriate next step in management?