Sorry to hear about your incident...certainly it doesn't sound like it was fun. Of course, a helmet is a great idea for activities that may result in accidents like this. It's not always cool or convenient, but it's worth the effort...as we all probably know.
"Blacking out" even for an instant can be considered a concussive event. So you probably suffered a concussion. It is always best to seek medical advice after an event like this regardless of how it feels. Certainly you should be monitored for a few days afterwards for signs and symptoms of head trauma, which include things as others have mentioned in their posts.
The neck was no doubt the recipient of some impact, very whiplash-like. Muscles will tense to protect the head but are then overwhelmed by the impact and cause a strain. Should the impact be enough and the muscles challenged enough, the joints will also suffer from the impact causing a sprain. This will cause the pain you are feeling when moving your neck. There are multiple things that will help the pain go away, even time alone may help, however the issue is how well it heals after this incident.
Accidents and even day-to-day use can build up over time in the body and cause dysfunction that can be imperceptible at first while later resurfacing as a more significant problem. Do go get checked by a chiropractor to not only get feeling better, moving better, but to also ensure optimal healing.
Surely you'll mis-ollie in the future and have some other fun incident so keeping up with your health and function now will preserve as much of your original function as possible for later in life. It's always good to think long-term!
