Just try to remember that it probably is the brain injury and not the real him, he is hurting too, inside his head...
He needs quiet and calm , as best as can be done.

I'm not an expert at all but have read many stories on this forum, so try as hard as you can to get him in to a specialist as soon as you can, ask for any opening that comes up sooner than the appt that is already scheduled.

Also you might look around for a chiropractor that does upper cervical adjusting, his c1/c2 might be misaligned from the falls too.
I've had that procedure and it is very different from the regular adjusting so no need to be worried about that if you are apprehensive on adjustments.
http://www.upcspine.com/self.htm
you can see some videos on youtube of upper cervical adjusting.

Explore the other threads and posts for more ideas, until someone else can post more suggestions for you.