It is still debatable whether H pylori can cause symptoms in the absence of peptic ulcer disease. Young children may of course not give a typical ulcer history, but clues would be epigastric, pain before meals or helped by eating or antacids. Not helpful when functional abdominal pain or reflux disease.
A meta-analysis of 45 studies concluded that H pylori infection is not associated with abdominal pain. In a German study of 1221 children social and familial factors (single-parent household, family history of PUD, or functional pain) were significantly associated with abdominal pain, but not with the H pylori status of the child, as assessed by the 13C-Urea Breath Test.
In a study of 695 schoolchildren between 10 and 12 years old there was no association between H pylori and recurrent abdominal pain, in fact there was an inverse relationship after adjustment for selected possible confounders!
Although there have been studies that seem to show that symptoms improve with treatment, these have been of poor quality and the natural course of illness is to improve anyway.
Now that a link has been established between helicobacter and cancer (esp stomach, via chronic gastritis, also non-Hodgkins lymphoma) in adults, benefits and risks of treatment when it has been discovered should be discussed.