My dog started Phenobarbital and I need help

TLDR

Dogs hind legs are very wobbly to the point he has a hard time walking. Phenobarbital symptoms.

Husky.

74.5lbs.

6 years old, almost 7.

Phenobarbital 64.8mg. One pill two times daily.

My dog started phenobarbital (64.8mg) March 3rd. He has been having seizures often on for years, all of his blood work comes back normal. For the first three years, my vet wanted to take a holistic route so I had him on CBD droplets twice daily.

Recently, he’s had 3 seizures in the past month.

February 13 (did not time) (boyfriend and I are arguing)

February 23 (3 minutes) (calm environment, no music, lights off, playing on my computer)

March 2 (4 minutes, 33 seconds) (calm environment, doing dishes)

I took him to the vet March 3rd he had blood work done, and everything came back great nothing abnormal. He was started on phenobarbital 64.8mg, one pill two times daily.

(Husky, 74.5lbs)

On March 5, I woke up to him laying on the ground peeing all over himself, I called his name and he was just staring off to the distance, not responding. He was still breathing. It only lasted seconds. I called the vet, they said it could possibly be a focal seizure, and that the medicine takes 10 to 14 days to kick in.

He had an accident in the house which he never does on March 7th as well. I woke up to it, but I didn’t see if he was laying down peeing again.

He’s been very wobbly in his back legs, I don’t know if this is a side effect, but it’s to the point where he’ll try to jump on the bed and his back legs just give out. He is almost seven years old.

He has been having seizures for years, but they haven’t been this close together. I don’t want to think the worst about a tumor or anything, because he does come out of it.

I just want to know if this is a side effect of the medication, or if it’s a more serious issue.

It’s now March 13, he hasn’t had any more accidents, he acts fine, takes his medicine great, he pees a lot. The only thing I’m concerned with is his back legs. He hasn’t had any more focal seizures to my knowledge.