Dietary fructose intolerance, or fructose malabsorption, how it tends to be called nowadays, can be tested by hydrogen breath test with fructose.
You can diagnose yourself with a strict low fructose (not necessary fructose-free) diet trial. Exclude all this from the diet for 2 days:
1. Fructose: honey, all fruit and fruit products of any kind, honey, anything containing "high fructose corn syrup", or "fruit syrup". From vegetables, avoid tomatoes and carrots. Also limit amount of table sugar which contains fructose.
2. Sorbitol: this is a sweetener, found in "sugar free" chewing gum and "low-calorie" foods or drinks
3. Fructans: these are fructose containing molecules found in wheat, onions, artichokes, leeks and asparagus, also in chicory.
If you have fructose malabsorption, symptoms should go away in 2 days. After that you can re-introduce wheat, since only some persons with fr.mal. are actually intolerant to it. If this helps, it is recommended to stick with this diet for 4-8 weeks, then you can slowly reintroduce some foods back. For more read about fructose malabsorption in my journals.