So sorry to hear of your loss.
I owned a Border Collie/Golden Lab as my first dog. Her name was Angel... and that's exactly what she was.
When she was 3 years old she started having fits. When they became more frequent, the vet suggested epilepsy and we began a regimend of phenobarbital daily.
For the next 5 years, Angel continued to have fits. A few of them so prolonged that we had to take her to a 24hr emergency vet. They administered intravenous medications there and she'd recover.
As she approached 9 years of age, she developed some arthritis like conditions and problems with going up stairs, jumping, and walking very slowly. When her condition worsened, we consulted the vet further. Judging by her physical reactions, and this thing called "knuckling", the vet concurred that it was not arthritis but actually a nervous system problem. (Knuckling is when you take a standing dog's foot and curl their toes underneath. If they don't respond immediately to stand correctly on the pads of their feet, this shows a slow nervous system reaction.)
We had her xrayed. It turned out, she had a slipped disc in her neck which was essentially causing her nerves in her body to short circuit at times. Her symptoms got progressively worse, and we then were considering a risky and expensive surgery that had a 50/50 chance of helping her. Just a few days later, the disc slipped completely out of place and paralyzed her over the course of 24 hrs. She passed on shortly.
It was a very sad way for my baby Angel to go. It is my and my vet's opinion that the fits might not have been epilepsy. The slipped disc was probably a genetic problem that started to develop early on. We'll never know for sure. But, I just thought I'd share the info.