From your case description it is clear that your son is suffering from gastroesophageal reflux disease (GERD). This is quite a common problem. In most cases, the symptoms can be controlled with certain life style measures and medications, if needed.
These life style measures include: avoiding fatty and spicy meals, not taking a large meal in one go, avoiding cola beverages, not to lie down within an hour of taking a meal, keeping head end of bed up by a brick, avoid smoking, etc.
The medications are acid suppressants and prokinetics, which can be prescribed by your treating doctor.