Donna - I had a dog years ago that had seizures, but never had the extreme body jerking and all that goes along with it. She would give out the most ungodly noise I ever heard - something like the combination of a howl/scream/cry - it gave me chills. Then she would fall over, but never had the extreme jerky movements. I would just pick her up and hold her till she came out of it. She was always disoriented and confused after, and would sleep for several hours after it was over. The only thing that gave me any peace tho, was that my vet said she wouldn't remember it, and it wasn't painful for her. Not for her - but it took a whole lot out of me every time.
Just keep an eye on Spike - it's possible that it was a seizure. Good luck with the vet visit.