Your child is likely to have gastroesophageal reflux in which the stomach contents pass back up into the food pipe. This is not uncommon and can usually be corrected with medicines. First try common things. Give more frequent but small meals instead of heavy meals. The child must not lie down immediately after a feed. While sleeping, ensure that the head end is elevated by about 30 degrees. If these do not help, your child may need medication for which you may need to see your doctor.