I had hoped you all would have had a diagnosis. I am sorry the results didn't come up with something. But so many of our knowledgable people here are giving you much needed information and I Know they have been there for me when I needed help.
I pray that the Doctor in Houston, Loma Linda or any of the specialists who are so interested in getting to the root of what is causing these symptoms. I am so happy the guitar came and hope it brings a smile to your son. Great that the instructor will be there on Saturday. Doing something he really enjoys will do wonders for him.
Hugs to you, your son and family.