I too was diagnosed with IBS over 8 years ago, and since been told that I have Crohns disease, which is sometimes mistaken for IBS. There is also another disease that mimics IBS which is called Celiac disease. There are blood tests that they can run and also a barium swallow to check out the small intestines for anything that might be also going on with the digestive tract. People with Celiac disease as allergy to gluten and gluten products which is found in many things over the counter at the supermarket. Ask that he is tested for gluten intolerance and asked to this to be ruled out first. I hope everything goes well for him,as with me, it is a neverending battle day after day. See and doctor that specializes in internal medicine.