Read somewhere that he had a slight concussion...Is that like being a little bit pregnant. A concussion can cause confusion.
It's possible that 6 months from now he can start having seizures or other problems.
Even slight bleeding in or on the brain leaves a clot which can take years to be absorbed.
I had a wreck on my bike when I was 11 and it was 22 years before I had normal results on an EEG.