
I definitely agree with the others..go back to your vet, or try another vet.
Fits can be different in different animals. I have a cat who fits occasionally, and it isn;t like you'd imagine a fit to be. It usually happens in his sleep, his legs will twitch a couple of times, he'll jump up, then fall over and he's out of it for about 30 seconds after that.
When he comes round he's confused for a few minutes but then soon gets back to normal.
They are very strange things, and it must be p[retty frightening for you at the moment to be seeing your dog go through this.
If you're not happy with what your vet says, get a second, or even third opinion.
Wishing you all the best, and hope everything turns out ok.
Regards,
Lisa