Difficult to say without evaluation.
There can be a variety of causes, ranging from musculoskeletal causes to neurological conditions.
Chronic muscle pain and
weaknessWeakness should necessitate a workup that includes checking the muscle enzyme levels, as well as rheumatologic blood tests, like the ANA level. Imaging the brain or spine can be considered if a
neurologicFocal neurological deficits
Multiple system atrophy cause is suspected.
A referral to a neurologist or orthopedist can be considered, depending on what your son's personal physician finds.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin Pho, M.D.
KevinMD.com
Twitter.com/kevinmd