Hello: Low blood sugar in a ferret is usually caused by very tiny tumors on the pancreas. This type of tumor is called an insulinoma. It cannot be seen on an x-ray unless it is huge. It was still a good idea to x-ray her, though, just to make sure everything else is normal in her chest and abdomen. I'm not sure why she was placed on antibiotics. Maybe she also has a cold or some other infection. These ferrets need a medication called prednisone. It comes in a liquid and you give it twice a day. The prednisone helps raise the blood sugar. It does not "cure" the insulinoma, but rather manages the symptom of low blood sugar. It doesn't always work either. Sometimes the ferrets need other medications as well. The best treatment is surgery to remove the tiny tumors. Many people can't afford the surgery (can cost upward of $1,000), so they choose to manage the ferrets with prednisone. If you need to find a more experienced ferret veterinarian, you can find one at this web site http://www.aemv.org/vetlist.cfm. I recheck a glucose one month after starting the prednisone. If she's not on prednisone, I'd get her to a vet who can prescribe it asap. If you're interested in surgery, discuss it with a ferret veterinarian. Best wishes.