Forgive me for saying this, but you are eating foods off the diet and then posting messages wondering why you are sick! This is crazy!
You need to follow Heather's diet and you need to read ingredients for everything you are eating. As I suggested before, sticking to things you make yourself (using ingredients from scratch) is the best approach for now as opposed to eating prepared foods such as a chicken roll, snack o jacks, etc.
I've posted the complaint before that many people on this message board are seeking fast, simple solutions for what is a very complex condition. From personal experience, the solutions are not simple and you will need to spend much more time in food preparation and scrutinizing everything you are eating.
Unfortunately, we have been reared in a fast food society, but we (IBS people) suffer from a condition requiring a slow food approach.