It might be because when your stomach is full, your abdominal cavity increases the pressure on your thoracic cavity. It could also be from reflux.

I would think about eating 4-5 small meals throughout the day instead of three large meals. And limit, to the best of your ability, drinking at meal time. Water, especially carbonated water, can both increase the fullness of your stomach and cause reflux.

Best,
Linda Esposito