How do you know if you have irritable bowel syndrome?

Maybe not IBS: The key to your answer: what symptoms, duration of distress, & recent evaluation. If you are awakening from sleep due to pain, your symptoms don't come & go (are unchanging & ever present or are actually worsening), there's bleeding/fever then it is unlikely you have irritable bowel syndrome. In such a case, further evaluation is warranted rather than you just taking symptom-based medicine.

Abdominal pain: You will have abdominal pain almost daily, distention and aggrevated by certain foods.

Any symptoms: What symptoms do you have? How long did yo have them ? If not you donot have ibs.

YOU WILL KNOW: You will have daily abdominal pain some times balloted, all tests are usually negative.