Sounds like you are doing the right things. The fact that he had no PCS symptoms before the recent fall is a good thing. The fact he was physically active before the fall is a big plus. Lots of quiet rest is very important. Go easy on the workouts, and have him stop immediately to rest if he gets dizzy or starts getting a headache or blurred vision. Good nutrition, B complex vitamins and good hydration are also important. All brain injuries are different and they heal on their own schedule. As head injuries go his is very recent and significant improvement should be expected.
What Happened: On November 29, 2010, I was walking across the street and was hit by a light rail commuter train. Result was traumatic brain injury and multiple fractures (pelvis, ribs, skull). Total hospital stay was two months, one in ICU followed by an additional month in neuro-rehab. Upon hospital discharge, neurological testing revealed deficits in short term memory, executive functioning, and spatial recognition.
Today: Neuropsychological examination five months post-accident indicated a return to normal cognitive functioning, and I returned to work approximately 6 months after the accident. I still deal with periodic depressed moods but for the most part glad to be alive and looking forward to the rest of my life.