Owen is a healthy 6-month-old, breast-fed infant with mild gastroesophageal reflux who presents to the Emergency Department twice in 2 weeks. Initial symptoms for the first visit include severe vomiting followed by diarrhea. No fever. He was diagnosed with viral gastroenteritis and was discharged home after tolerating breastmilk. The following day, he was better. His diet otherwise includes sweet potato, squash, apples, and bananas. He does receive pumped breast milk at times. Family has tried thickening bottle.

He presents again to the ED with prolonged episode of vomiting. He now appears pale and lethargic without any rash. In the ED, he requires IV fluid, which helped his condition improve. He was given an abdominal ultrasound, which was negative for pyloric stenosis.

Have you figured out this diagnosis? It was acute food protein-induced enterocolitis.