Gastroesophageal Reflux Disease (GERD): This condition is common in infants and can cause vomiting, which may appear yellow due to bile. The age of the child and the nature of the vomit make GERD a plausible first consideration.

Viral Gastroenteritis: Although more commonly associated with diarrhea, viral gastroenteritis can cause vomiting that may contain bile, especially if the infection involves the upper GI tract.
Pyloric Stenosis: Typically presents with projectile vomiting after feeding, which can occasionally appear yellow. However, the classic presentation is with non-bilious vomiting.
Intussusception: A condition where a part of the intestine slides into an adjacent part, which can cause intestinal obstruction. Vomiting may be bilious, and it's a critical diagnosis to consider due to the potential for complications.

Intestinal Obstruction: Conditions such as volvulus, intussusception, or other mechanical obstructions can cause bilious vomiting and are medical emergencies.
Appendicitis: Although less common in infants, appendicitis can present with vomiting and should be considered, especially if there are other symptoms like abdominal pain or fever.
Hirschsprung's Disease: A congenital condition affecting the colon that can lead to intestinal obstruction and bilious vomiting.

Biliary Atresia: A rare condition in infants where the bile ducts are absent or blocked, leading to jaundice and potentially bilious vomiting.
Congenital Anomalies of the GI Tract: Conditions like duodenal atresia or stenosis can cause bilious vomiting and are usually diagnosed in the neonatal period but could potentially present later.
Inflammatory Bowel Disease (IBD): Although rare in infants, conditions like Crohn's disease or ulcerative colitis can cause a variety of gastrointestinal symptoms, including vomiting.