Possibly the continuing irritable bowel is due to gluten intolerance.
People with gluten intolerance commonly also have lactose (milk)
intolerance. Check out some of the celiac sites for more info and
testing possibilities.  Two web pages to start out are
http://www.celiac.com or  http://www.panix.com/~donwiss/  and links
therein. Avoiding milk and gluten is hard, but not impossible.