Hopefully he is just tired after his busy training night and his strange movement was tiredness. Its awful worrying when these things happen and I can understand how upset and worried you must be as I know harley is your world.
I know you will be keeping him calm and rested and hopefully he will be back to his normal self tomorrow. When Jasper's back is playing up he is quite restless and cannot settle in one place for long and he kicks his leg (usually his right one), he as his metacam and sometimes he needs tramadol until things settle down. He is always usually slightly wobbly and as some weakness.
Thinking of you and Harley and am hoping that he is okay, if he needs to see his vet then hopefully he will get to see the vet you prefer.
Jasper tri 21/Dec/05, Gabby ruby girl 8/Nov/07, and Felix the cat 4/April/10