You should tell him to cute out carbs and sugar from his diet as much as he can! Many people get a yeast overgrowth in their intestines called Candida, and it can cause people to have those symptoms after eating.
Another possibility is he might have a gluten intolerance. He should cut out gluten from his diet as well and see if it helps at all! Gluten intolerance can cause those symptoms
thank you for your generous reply ma'am .
The thing is my father doesn't eat a lot of carbs or sugar . about Candida , is there a specific blood test for it ?
could it be coeliac disease ?
Has your Dad had his blood sugar levels checked?
As far as bloating and gassy, is this after he eats anything or fatty foods which may mean it's gallbladder related.
I sound like a broken record, but honestly, just ask him to go to his Doctor and get himself checked.