Purpleviolin
This sounds a great deal like my DS14 who is finishing up his freshman year in high school. He tested not quite at your DS's FSIQ level at age 8 but close (144). In late middle school, he started to kind of lose it in Algebra and could not keep himself organized and was struggling in nonstructured environments. Luckily we had a full work up the summer before high school and figured out he had ADHD-Inattentive and Dysgraphia. He's on low level meds now and is excelling in all his classes including 4 Honors classes with tons of work.
Of course, ADHD is often co-morbid with another condition and his tendency toward anxiety emerged but I am hesitant to put him on meds for that with summer break coming soon and we provide a great deal of support at home. In any event, yes you should definitely have a full work up for your son. In addition, at age 15, I would be concerned about all the time spent "working on stuff". It could be innocuous but it's a much different world out there than when I was in high school.
Good luck and keep us posted!
