Can a baby develop reflux at 10 months old?  

Yes. Infants can develop reflux. Symptoms include excessive "spitting up, " vomiting, abdominal distention and fussiness. Check with your pediatrician to confirm the diagnosis.
Reflux. A child can develop at anytime, whether at 10 weeks or 10 months. It is usually due to the valve that connects the esophagus to the stomach that doesnot work properly.