Food intolerance is a vast subject but if you suspect food is causing your bowel problems but can't quite work out why - this may help. Delayed reactions and seemingly different reactions to the same foods are all pointers to food intolerance. There are natural chemicals as well as artificial ones that can overload our digestive systems because our diets are saturated with them! We all have a tolerance level and after we reach it we'll have reactions. It may take a few days or a few hours to occur depending on what we've eaten and our sensitivity levels.
The following links explain it better than I do.
I hope it helps - I wish I'd known about it 20 years ago!