Can't help but notice you keep recommending this guy's book to people and telling them to basically drop Heather's diet. Was that your main purpose of registering on this board?
As other people on here noted, it took some over a year to stablize and yes diet isn't the only thing that contributes to IBS but it is a key factor. Heather has covered medications and stress factors here on the website, and in her book.
If your intent was not to stir things up around here then I apologize for this post.