What's a cure for chronic diarrhea after gallbladder removal?

My new husband has chronic, almost debilitating, diarrhea. He said he had his gallbladder removed about ten years ago. I don't know a thing about this surgery or complications after wards. What is a cure for the diarrhea and what are the foods to eat and what are the foods to avoid? I've been trying to research this but it's very confusing.