It is a long and slow process of recovery... Easy to 'talk' about, but hard to live thru! About 20 years ago I had one very hard fall! Horse and I both fell and hit hard ground. I was in-out of consciousness for about 3-4 hours after.. I remember falling, coming to and being strapped on a board, being asked who the president was? -answered Wrong! and then re-waking up in the ER... Fractured ribs [still 'feel' 'em now and then?] w/a solid concussion.
Disorientation set in? Couldn't remember simple things ..like my last name or my age? Dis-connect from lots of things...couldn't remember staff's names? Phone #'s? Would start sentences and not remember where I was or what I was saying half way thru? Couldn't remember spit, just felt like I'd been run over by a car! The horse was big, I'd bruises like the state of Idaho in one place and Texas in another!
Down to brass tacks tho? Was your son wearing a helmet? That'd help. If not? Expect things to take 2-3 months to start getting back to normal.
Definitely explore opinions by trauma neuros and spinal injury docs.... The think of key concern is the change in attitude about things. Ask your doc for a few names and check them out thru various web check sites [those that are free- ones you pay for are rip offs]
Simplistic way it was explained to me & still makes sense? - Your brain is like an egg in a shell [the skull] It's gotten a good shaking and hopefully the yolk isn't broken, nor the spine injured. Sometimes spinal/bone trauma takes a while to show up. I hope it's simple and that time and good rest can fix it!
I DID get back up on the horse tho! Hugs for your son, and you...and HOPE too! - j 's!!!!!!!!!