I just read this post, it's old I know, but still very relevant. I relate to so much of what you've written.
I've had IBS since I was a teenager and am now in my 60's. It flares up about twice a year although there were years of complete freedom.

All fellow sufferers will agree with me when I say that each and every time it happens my mind tells me THIS time it's something worse.....
This brain/gut connection is complicated but very real! The symptoms feed the anxiety, the anxiety feeds the symptoms. You get caught in a loop.

Sometimes a visit to the Doctor is all I need, some reassurance that all is well and the symptoms disappear. Like magic!
This time it didn't work for me so in desperation I tried a Homeopath. She has been very sympathetic and agreed that my IBS due to a combination of food and anxiety She's given me medication and supplements but she also tested me for food allergies and told me I have an intolerance to wheat, corn, barley, rye, oats, potatoes, tomatoes, brinjals and cocoa.

Well trying to sort out a diet that eliminates all of the above has left me even MORE anxious!
Trouble is when I'm not having an IBS flare up I can eat absolutely ANYTHING with no ill effects.

Is it really all due to anxiety? Or is it that when we have a flare up our stomach becomes more tender and intolerant to certain foods?