Cow's Milk Protein Allergy (CMPA): This is the most common food allergy in infants, and symptoms can occur even in breastfed babies if the mother consumes dairy products. The proteins can pass through the mother's milk, causing an allergic reaction in the infant.

Lactose Intolerance: Although rare in infants, lactose intolerance can cause similar gastrointestinal symptoms to a milk allergy, such as diarrhea, gas, and bloating.
Gastroesophageal Reflux Disease (GERD): GERD can cause symptoms like spitting up, irritability, and feeding difficulties, which might be mistaken for a milk allergy.
Protein Intolerance: Intolerance to other proteins (e.g., soy) could also cause symptoms similar to a milk allergy, especially if the mother consumes these proteins.

Infectious Gastroenteritis: Bacterial or viral infections can cause severe gastrointestinal symptoms and must be ruled out to avoid missing a potentially life-threatening condition.
Intestinal Obstruction: Although rare, conditions like intussusception can cause severe abdominal pain, vomiting, and bloody stools, mimicking some symptoms of a severe allergic reaction.
Hirschsprung's Disease: A congenital condition characterized by the absence of ganglion cells in the colon, leading to severe constipation or intestinal obstruction, which could be mistaken for an allergic reaction.

Eosinophilic Gastroenteritis: A rare condition characterized by the presence of eosinophils in the gastrointestinal tract, which can cause symptoms similar to a food allergy.
Food Protein-Induced Enterocolitis Syndrome (FPIES): A rare, non-IgE-mediated food allergy that typically presents with severe vomiting, diarrhea, and abdominal distension after ingestion of the offending food protein.
Galactosemia: A genetic disorder that affects the body's ability to metabolize galactose, a sugar found in milk, which can cause severe symptoms if not diagnosed and managed properly.