I started feeding your formula and my pup has gained weight, but he is still twitching and having seizures. Is there anything I can do to help him?

I have a problem with my three week old Yorkie. He was weighing 14.5 oz three days ago. I started your formula yesterday and he loved it. He gained weight. I was so happy, but he is still twitching and has lots of seizures. I feel helpless. I called the vet and they said he might have a shunt liver. Is there anything I can do to help him? I really don't want to put him down. I don't sleep, I feed him every two hours. Please help my babie Yorkied (AKA Peewee).