I think we all have seen some pretty gnarly hits on players in our time. Alex Smith and Joe Theisman are the first two that come to mind. I don't disagree that he probably had a concussion from the first injury. He would have crumpled like aluminum foil from that second hit regardless of what he had been through previously though...its just so much worse if he was still concussed and he suffers another impact. He is lucky to be alive IMO. That was a type of concussion caused seizure he had after that hit. I would bet money on it. The way his hands locked up is what happens to mine during a convulsive seizure. (I have epilepsy, since age 13. 100% medically controlled, but had a few big time convulsive seizures first) I don't remember any of my seizures and sometimes it wipes out my memory for days before the seizure and days after. The only reason I know what I looks like when I personally have seizures is because a two minute convulsive of mine was caught on a security camera. I would be shocked if he remembers anything for a few days before or after that injury. He probably won't remember the hospital at all. My convulsions have created 2 weeks holes in my memory....without an impact creating the event. I was up and walking and talking for two weeks afterwards and I don't remember any of it...most people had no idea my brain was scrambled. That impact plus a concussion, plus the neck and skull damage, plus he probably already a concussion 5 days earlier. He shouldn't come back this season, and he wouldn't if the NFL was actually serious about player safety.
I would take the guaranteed money in my contract and sit out awhile as a young rich man. On a beach somewhere tropical probably. I know the young competitive dude is gonna fight with everything he has to get back on the field though.