I would recommend Marinol. It is Rx'ed by his MD. Also, I have started Lidocaine infusions- I.V., 4 mg. per Kg.. I've had two and they really help a lot. Their affect lasts three weeks for me.
Is he on a tricyclic anti-depressant and anti-epileptic- line Nortriptyline and Phenobarbitol?? If not those are the first meds. I also use Dextromethorphan. It's experimental, used in studies by Christine Sang MD at Mass. Gen. Hosp. I use 60 to 90 mg twice a day, and am 80 kg ( more or less). So use 1 mg per Kg, twice a day for your son. This med is bought over the counter. Ask you pharmacist for help. I hope this helps. Any questions,problems, etc. write back. Frank