I may also pull out my M:TG cards and build a couple of decks to see if he is interested in playing. It *is* very mathematically involved and requires the same mental notekeeping and strategic thinking as other games such as chess require.
It seems I've gone off topic, though! Just in: my mother has offered to find and fund a private evaluation for DS.
Also, what about ADD/ADHD? I personally was diagnosed with ADD at the age of 27 (I turned 30 yesterday.) Adderall, only 15 mg a day, has absolutely transformed me. I have always been ADAMANT that DS not be diagnosed nor medicated, but perhaps the time has come to investigate the possibility?