I Have Read Your Question,
People , Usually after 60years often experience such problems, the possible causes for this problem , could be an infection like Giardiasis
which is generally caused by an flagellate protozon giardia, or mild diarrhea
I recommend you to try taking pre/probiotic
tabs or drink and also fenugreek seed powder(less than a teaspoon) after the meal.
If the problem persists , I suggest you to consult a gastroenterlogist nearby for further guidance ,
Wishing you a good health,