First let me say I am sorry you are dealing with this.
My sweet first Peyton just passed away a few days ago because of hydrocephalus. I am no expert at all, but have a little first hand experience with it.
One thing I learned is early detection and correction is really important. Once the brain damage is done, it cannot be reversed as brain cells don't regenerate. It was too late for Peyton because so much damage had been done.
Don't try to evaluate this on your own. Peyton's case was clearly progressing, yet two different vets missed it completely. He was a happy pup, who played and acted "normal" until slowly one thing or another deteriorated. First his hearing, then sight, then sense of smell, then ability to keep food down, then desire to eat and drink, then potassium regulation problems, etc. The end damage came on very fast. Who knows what might have been done to help him with early diagnosis and surgery? His case is a bit of a mystery because it was so undetected. This could be unique,mor bad vets, I don't know.
If there is a specialist you can go to, I would go right away...tonight if possible. I may be speaking from emotion, but that is what I would do.
Bless him and you for helping him. Please keep us posted.