My Husband Had Some Food Poisoning And Diarrhea For One

My husband had some food poisoning and diarrhea for one day, He didn't have pain or anything else and since then for 4 days every night he has watery stool with some type of foam or white mucus and then in the morning the stool was okay and no foam. Today is the fifth day of the same pattern. He went through colonoscopy a year ago and he did the blood test in April and everything was fine. What can he do to get normal stool?