DO NOT TAKE MEDICAL ADVISE FROM ME. THIS IS ONLY M ANECDOTAL EXPERIENCE. ALSO I HAVE AUDHD WHICH PROBABLY WORKS DIFFERENT THAN ADHD.
I have found a couple (like 3-4) of draws? puffs? inhalations? of weed from a vape helps me immensly. Not in the 20 or so minutes afterwards when the slight high is perceiveable but up to like half a week afterwards. I can do stuff and concentrate so much better.