Is there an alternative therapy to treat chronic belly pain?

To what? Alternative to what? Medication, surgery, nerve block, and accupuncture all may help.
Cannot Answer. An alternative to what? You must know why you are having belly pain before you treat it. So you would not be chossing an alternative until you knew the primary treatment fist and to know the primary treatment you gotta know the primary cause. See your doc w/ belly pain.