Joint Pain in Niemann-Pick C Child

My son who is 10, was recently diagnosed with a rare metabollic disease; Niemann-Pick Type C.  He is in the early stages of the disease, and we have started Zavesca (treatment for Gaucher's), which is known to slow the progression of NPC but is not a cure. We began physical and speech therapies, but he has been complaining about his fingers really hurting when he writes.  His fingers look very skeletal, and the PT thinks he has atrophy.  We began some finger exercises, but we were wondering if there are some that are more effective and if there was anything that could help with the pain.  He is also on DHA, D3, curcumin, and calcium (since he is dairy allergic.)

Any suggestions would be very helpful, until we meet the specialist at the end of the month.

Thank you.