Thanks for writing in.
As you say, heart and lungs normal (in X ray
chest? I assume) with normal EKG and echo.
Your main concern is the Chest pain
I would suggest you take consultation from a pediatric cardiologist and then follow their advise. There may be other tests which have not been so far detected.
However please do not panic if every thing is normal with reference to the heart as chest pain can also have a non-cardiac cause