I'm in extreme sports. While I didn't have a loss of consciousness hit yet I have been through a few with friends.
The instant knockout:
Had a friend backflip a quarter pipe and the back of his head hit the railing, knocking him out mid spin. He ragdolled the rest of the flip and landed on his back on the airbag. He woke up roughly a minute later.
5 minutes in he was doing in an interview on what went wrong. 15 minutes in he forgot he got interviewed and what he talked about. He had a few more short term memory loss surrounding the events. A few hours of confusion followed.
He kept asking questions, time location, everything that could jog his memory. He had symptoms of dizziness and haziness, but experienced no headaches.
What's to note is that he felt no pain and just slept through it. Also the multiple questions, they keep happening throughout the day.
This was his second accident. In the first one he forgot the whole day. That time he was sporadically asking when we were going to the event. The one that he already crashed in.
Not so instant knockout
I don't know the whole follow up symptoms for this one because the cases I've seen didn't wake up. They are in a state of semi awareness where they move they moan they give out sounds that resemble words and don't react to stimuli. Especially verbal. They can also have they eyes wide open but again, no reaction.
I leave these cases to trained professionals and just keep tabs and monitor everything that happens so I know how to give a detailed description of everything.