The H2 breath hydrogen test will reveal the possible intolerance to various sugars or modifications to the normal intestinal flora, which could justify the symptoms that you have. 

Its implementation is to measure (after retaining seconds breathing) breath hydrogen, basal manner and repeatedly after a sugar intake. The duration can be prolonged for 3-4 hours, since multiple measurements are taken, according to medical judgement. If you are intolerant to some sugar, you may present clinical gastrointestinal syntoms (nausea, abdominal pain, diarreha).