My 9 year old son has recent lower back pain and now says that the pain is radiating up his back and off to his right side. what could this be?

Back pain: I'm sorry but there's two little information to give responsible answer. In these situations the patient has to be examined.

See pediatrician: Low back pain with radiation to the side in a 9 year old is unusual; it could be a muscle sprain or a slipped vertebral disk. He should see his pediatrician who may refer him to a specialist if he needs to.

Many Causes/M.D.: There are many conditions that this may be related to. I would advise an assessment of his spine, nervous and muscular systems. Other causes may involve a kidney injury or infection.