The British Dietetics Association has a helpful fact sheet which explains the difference between food allergies and intolerances and how these can be managed. If you are having stomach or bowel symptoms as a result of eating certain foods it may be that you have Irritable Bowel Syndrome (IBS) - this would need to be diagnosed by a doctor. There are many commercial allergy tests available but these should be used with caution as many have not been scientifically proven to be accurate. The British Dietetics Association has a very helpful fact sheet explaining these tests.