I understand your Dad isn't having Diarhea. But still I would be curious , has he been tested for C-diff? As a person who struggles with this Disease myself, it's not uncommon for me to have 3-4 fairly normal BM's daily . When tested I have active C-diff. It's a simple test to find out. You/he might want to mention this to his Physician. I wish him and you all the best!