My pet rat is very weak, wheezing, and can't stand or walk right.?

Zoey is my little rat and she is very sick and I am not sure what to do. I have had her about 6 months but don't know how old she was when I got her. I have her sister from the same litter as well. Zoey is wheezing alot, is very weak, and can't walk or stand. She keeps falling over and when she tries to walk she seems to go in a circle because it seems like she can't lift her head. She is on anti-biotics right now but it doesn't seem to be working. I have been giving her water through a dropper the same with the medicine. Does anyone have any suggestions?? I am very worried that she is in pain.