I recommend he be evaluated by his pediatrician
for the following metabolic profiles if not already done: THYROID
FUNCTION (using FT4 and TSH), LIVER ENZYMES and INR to establish liver integrity, COPPER LEVELS in 24 hr. urine.
His pediatrician could also order an MRI of the brain (without contrast to start) which can be repeated WITH contrast if something suspicious surfaces on the first one.
If any of the metabolic profiles come back POSITIVE for something out of balance then, it should be corrected (with a consultation to appropriate specialist if necessary).
If the profiles are NEGATIVE for metabolic abnormalities and the imaging studies are negative for architectural problems then, a referral to a PEDIATRIC NEUROLOGIST
would be in order.
The most COMMON pediatric movement disorder
consistent with your description is ESSENTIAL TREMOR
which is usually successfully controlled with medication.
Hope I have answered your query. Let me know if I can assist you further.
Dr Dariush Saghafi, Neurologist