Welcome to Gaia! ::

My mom has IBS as well and cutting out yeast helped her a lot. It took a few years for her to pin down the things that upset her stomach and the ones that didn't but by being very conscious of the things she was eating and when she felt sick she has mostly been able to figure it out. Preservatives and sulfates are baddies too.

I don't know if I have IBS, I never had it professionaly checked out, but something has always been wrong with me in that area. I know that certain foods do cause me to be bloated and way more gassy that usual. I tend to stay away form those foods, even though some of them are very yummy, lol. It may take time, but as others have already suggested, just pay attention to what you eat and how your body reacts afterwards. Maybe keep a written record. Something like:

Tomatoes
Whole/Natural - No effect
Paste/Sauce - A little more gassy than usual, some bloating
Ketchup - Gassy

Other than that, maybe see a professional nutrionist and/or personal trainer to help you with exercises and diet plans. It is recommened that a person should get on average 15-30 mins of exercise per day, drink 6-8 full glasses of water, and stay away from junk/fast foods, soda, smoking, and alcohol. Of course, almost anything can be good in moderation. Even small occasional amounts of alcohol have been proven to have their benifits, lol. Not saying you should run out and get drunk or start drinking.