The only breed I have heard of this happening to is the Doberman breed. Their skulls fuse together and their brain continues to grow putting pressure on it. Usually it takes time for this to happen though. I hope your furbaby is going to be ok.
Could it be parvo? I know that parvo attacks the nervous system and has some of the same symptoms as what you are explaining. It is curable if you get to it soon enough. Try bringing this up to the vet.
I have a 16 week old puppy that I got a 12 weeks. She had a rough and uncertain past when I first got her. She was almost dead D: literally.... The vet couldn't figure out how she was still alive. Well after spending a few weeks on 4 types of meds 3 times a day and lots of affection and good...