I understand your concern for your husband.
Let me reassure you that his symptoms are only slightly deviated from normal. There is no major underlying gastro intestinal problem in him.
1. Bowel movements increase after taking food. This is very normal. You need not worry about this.
2. He needs to take at least 2 litres of water in a day. If he is doing this, then there is no need to worry.
3. Ask him to take a big plantain every day so that he can pass his motions easily.
4. Do not force him to eat more food.
5. However, encourage him to consume lot of fruits and salads and to never miss a meal.
Let him make a few dietary changes as said above and he should be fine soon.
If the problem remains after 6 months, he may require a colonoscopy
to be done.
Hope I have answered your query.
Wish your husband a speedy recovery.