Gastroesophageal Reflux (GER): This is the most common cause of vomiting in infants, especially at 2 months of age. It occurs due to the immaturity of the lower esophageal sphincter, leading to the reflux of stomach contents into the esophagus.

Infectious Gastroenteritis: Commonly caused by viral infections, this condition leads to inflammation of the stomach and intestines, resulting in vomiting, diarrhea, and sometimes fever.
Overfeeding or Underfeeding: Incorrect feeding techniques or volumes can lead to vomiting in infants.
Lactose Intolerance or Milk Protein Allergy: Although less common, these conditions can cause vomiting, especially after feeding.
Pyloric Stenosis: A condition where the pylorus (the passage between the stomach and small intestine) thickens, blocking food from entering the intestine, leading to projectile vomiting.

Intussusception: A serious condition where a part of the intestine slides into an adjacent part, potentially cutting off blood supply. It's a medical emergency and can present with vomiting, abdominal pain, and bloody stools.
Volvolus or Intestinal Obstruction: Twisting of the intestine or blockage can lead to severe vomiting, abdominal distension, and potentially life-threatening complications if not promptly treated.
Congenital Heart Disease: Severe cases can lead to feeding difficulties and vomiting due to heart failure.
Inborn Errors of Metabolism: Certain metabolic disorders can present with vomiting, among other symptoms, and require early diagnosis for proper management.

Congenital Anomalies of the Gastrointestinal Tract: Conditions like esophageal atresia, tracheoesophageal fistula, or duodenal atresia are rare but critical diagnoses.
Neonatal Opioid Withdrawal Syndrome: Infants exposed to opioids in utero can experience withdrawal symptoms, including vomiting, after birth.
Adrenal Insufficiency: A rare condition where the adrenal glands do not produce enough hormones, potentially leading to vomiting among other symptoms.