Help please!

My baby chick is like 6 weeks old, and is very dizzy. They have trouble keeping their head up at any given momen, and will back up into corners to stay upright. My cat grabbed them by the neck and almost brought them inside about 2 weeks ago, but they seemed fine after. The neck problems only happened a week after. I went to the vet and they gave us antibiotics saying it might be an infection. She can walk sometimes and has an appetite. she can’t drink water without assistance. What else can i do?