Recurrent abdominal pain in children in most often due to –
Roundworms
Emotional/behavioural problems
Amoebiasis
Giardiasis
Chronic and recurrent abdominal pain in children 

Chronic abdominal pain is defined as recurrent or persistent bouts of abdominal pain that occur over a minimum of 3 months.
The commonest cause of chronic abdominal pain in older children is functional (non organic) that may be due to emotional or behavioral problems.

Causes of chronic and recurrent Abdominal pain