Hi and welcome to HealingWell!!
First off, let me say how great it is for you to be here on your husband's behalf. Too few family and friends don't even try to understand what IBS is all about and how difficult it is for us. Kudos to you!
At your husband's age isn't it suggested he have a colonoscopy at least every few years? Has he had one recently? In my opinion, it seems excessive to have D over 10 times a day and have to wear a diaper. He sounds more like he has IBD (Crohn's or UC) rather than IBS. Does he have blood in his stool? We all understand the humility, but doctors have heard it all.... Your husband should really see a Gastroenterologist.
You are correct about the calcium carbonate. It will help soak up the excess water in his BM's and it will also help soothe any inflammation he may have in there. You may also want to try probiotics. For someone who is having that much D it is important to replenish his "good" bacteria. The best way would be to give him a supplement with a high culture dosage. My favorite is Culturelle; it has at least 10 billion live cultures per dose and is gluten free. Another good way is via yogurt. Dannon Activia is an excellent choice, it has millions of 3 different active cultures.
Have you read the Calcium post yet? It may help answer any questions about when and how to take it.
Co-Moderator for the IBS Forum