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What type of IBS do you have.... D (diarrhea), C (constipation) or A (alternating between C & D)?
In my opinion, fasting isn't a good idea. If your intestines take a rest it might be even harder to get them back up and running when you do re-introduce food. What about
going on a low fat diet? Or even a liquid diet? If you have IBS-D then you're probably already under nourished, you don't want to keep depriving yourself. Make sure that whatever diet you do try you get plenty of vitamins and nutrients. Maybe take a supplement.
Have you tried OTC meds for the bloating? Maybe take some Beano before a meal and/or Gas-X after. I've also noticed that taking probiotics helps with the bloat (if you can push through the first couple weeks with gas). Digestive Advantage is great and has worked for many of us.
Sorry, I can't help you with the stomache rupture question. I want to say NO, that your stomach can rupture by over eating, but not because of bloating.