Dairy is a big trigger for histamine intolerance which is beyond lactose intolerance. Olives, sugar and gluten are also high histamine foods as well as anything that is fermented, pickled, and foods with vinegar. Tomatoes, avocados, bananas, citrus as well as black and green tea are high histamine foods. This can be misdiagnosed as only IBS. Some strains of probiotics are helpful but others are harmful. Look for Low Histamine Probiotics.