AYour symptoms could be caused by a number of factors so it's important that you consult a GP or a nutritionist to make proper investigations. It's possible you may be suffering with hypochlorhydria, which is a digestive disorder in which there is a low level of hydrochloric acid in the stomach. This is common in adults over 50.
I would suggest that you avoid eating large amounts of food at each meal, stick to eating smaller meals more often during the day.
If you have limited amounts of stomach acid and digestive enzymes, then large meals will greatly increase symptoms.
Don't drink large amounts of liquids for 30 minutes either side of a meal, either, as this will reduce digestion further.
Consider taking a digestive enzyme supplement before meals. Alternatively, you could take one tablespoon of apple cider vinegar in a little warm water 20 minutes before a meal to get your digestive juices flowing.
You might also benefit from eating more green bitter foods such as rocket, radicchio and endive, which promote digestion. Consider having them as a salad starter before your dinner.