Seems like I am having very similar experiences with my beagle, Daisy. It is so heartbreaking to see her like this. Wishing these side effects would subside. She was up walking all night last night & gets into corners & can't get out. Next week she will be on PB for one month. Will be calling vet soon to get her levels tested to see what to do next. I just thought after this long, the side effects would have leveled out by now. I am sorry you are going through this, as I know what it is like.
Well, so far no additional seizures, but he wants really bad to jump up in our laps like he used to. Right now, he doesn't have the strength or coordination to do that, so we end up picking up and that makes him happy. The only time he is animated right now is at feeding time or when he is getting his pb (he thinks he is getting a treat). However, the animated behavior doesn't last long. Thanks for the heads up about possible seizures continuing. We have noticed a few times that his head is lightly shaking up and down, but that is usually only when he is standing up and his front legs are having trouble supporting him. Also, the lack of support and coordination of his legs is more evident when he first gets up from laying down.
I'm not an expert, but have experience with dogs and phenobarbital, as ours has seizures also. The injections of pb were probably what they call a 'loading dose.' We were told to expect a walking drunk when we took our dog home. It's hard to give your pet more of a medication when you know it's the cause of their unusual behavior, but it does get better. It took 7 days for us to notice the drunk behavior dissipating.
I'm not trying to scare you, but don't feel defeated if your dog continues to have seizures. I wish someone would have said those words to me. A lot of times the vet will have to check blood levels, increase meds, and even add additional meds until the seizures are under control.