I had my entire colon removed in 1983. To answer your questions, I take about a heaping teaspoon of Metamucil in about 5 ounces of water twice a day and it acts like a sponge in my bowel to absorb extra liquid. His stools will never be what is considered to be normal, but this will give him some relief from the constant diarrhea. Make sure that when you add the Metamucil to the water, you drink it immediately. If not, it will solidify and cause problems going down. In answer to your probiotic question, yes he definitely needs to be on a good probiotic. In the past, I have taken all sorts, but I am now on VSL number three, which is 450 billion units per day. It is in a powder form, and it is not cheap. It’s about $100 for a 30 day supply, but it definitely will keep him from catching every little G.I. bug that runs around. I hope this has been helpful to you.