Hi,
Thanks for writing your query.
After reading your post, it seems that your husband is having increased acidity and gas production.
He should follow some precautions like :-
1. Avoid spicy and oily foods.
2. Do not miss a meal.
3. Avoid smoking/alcohol, if any.
4. Avoid mental/emotional stress.
5. Do not eat fast and do not talk while eating.
6. Avoid gas producing foods like peas, cabbage, lentils, gram, etc.
7. Drink at least 8-10 glasses of water daily.
He should take an antacid like 
Omeprazole 40 mg once a day before meals along with 
Dicycloverine after meals for 
abdominal pain.
If he is having loose stools, he can take an antibiotic like 
Ciprofloxacin 500 mg along with an antiamoebic like 
Metronidazole 400 mg thrice a day.
Probiotic will also be helpful.
I would suggest that he should be investigated for following :-
1. Stool examination(Routine/Microscopic and  for Occult blood).
2. Complete Blood Count(CBC).
3. Serum electrolytes.
He should have light diet with less spice and oil and prepared under hygienic conditions.
He should also maintain his hydration.
If the problem persists, he should get himself examined clinically.
I hope this is helpful to you.
Thanks.