Regarding Scrabble, When he wants to quit, he is likely mentally fatigued. It is better for him to complete many short tasks that get exhausted on a longer task. Pushing through is not successful with brain injury.

It is likely that he has a limit of only 15 minutes or so. Intense cognitive effort can be exhausting. And, don't try to mix talking and thinking. If he is trying to think of a word and you are talking, it makes his thinking very difficult and frustrating.

His sinus issues that may be allergies may be due to a strained immune system. My vitamin regimen has just about ended my allergies. Yesterday, I had my one day of hay fever for the spring season. We had 18 different tree pollens. I sneezed on and off a few times during the day and by today, my allergies are over.

I hope his sneezing is not causing trouble with his head. I have to be careful with the head movement when I sneeze.

Occasional use of an antihistamine should not be a big problem. I have used them a few weeks a year all my life until about 15 years ago. Any problems should only be temporary. Some of the newer meds may have a stronger neurological effect. I used chlorpheniramine maleate . I did not use decongestants like pseudoephedrine or antihistamines like diphenhydramine.

So, take it easier on him. Let him do simpler tasks with a break between. Let him set the pace. Too much video gaming may not be beneficial either. He may just use it to zone out.

My best to you.