I suggest you keep a diary of all the items you have eaten and drank, noting when the bowel issues arise too. See if there is a pattern. The diary MUST be specific, e.g., if you eat a baked potato then also note if there was butter and / or sour cream with it.

A lot of people, myself included, become lactose intolerant as they age. It's not easy to notice since it doesn't bother some people all the time. Keep track of all the dairy products you consume on the diary including milk in your coffee and cereal.