See pediatrician. Would recommend having the child evaluated by a pediatrician, especially when the patient is having chest pain. Also keeping journal to record what the child is doing, eating, experiencing, etc. When the pain occurs.
Common. This is a very common non-specific symptom that often gets a child taken to the er. Make sure that there is no heart or lung problem and if there is no obvious cause, I have found it repeatedly to be related to poor diet. This may sound strange but every cell in the body needs proper fuel to function properly and dietary mayhem is common.