2-day neurocognitive testing to measure cognitive crash?

We're trying to justify treatment to insurance, but a standard 2-day exercise test doesn't get at my son's primary functional issues.

His key items are the fatigue, anxiety, intractable headache, brain fog, bad sleep ... AND the neurocognitive/emotional crash he has after cognitive/emotional exertion.

Which can be an MD appointment, or managing the anxiety of a blood draw. Or trying to participate in the sole remaining class is in -- he likes the teacher, wanted to do well, but increasingly he says the 1 hour's lecture "goes in one ear and out the other" ... and yet wipes him out for 1.5 days after.