Muddy has always ate normally 1x/week on Reptomin pellets and always had a big appetite. On 7/11, she ate less than half and ate very slowly which was concerning. We took her to the vet on 7/13, the vet wanted to trial the antibiotic ceftazidime injections 0.25ml every 3 days. (Syringes are pre-filled and kept frozen and then thawed before administering). We did the 2nd dose on 7/16. But today 7/19, Muddy did not eat at all, which is very worrisome because this has never happened before. We were told the antibiotic shouldn't affect her appetite. So now I am very worried and don't know what's wrong. When we were at the vet, the vet was saying the bloodwork and x-ray could be done, but they can't tell a lot of answers, so he wanted to try the antibiotic. The vet only said that bloodwork shows kidney failure? And x-ray would show the lungs and if there are eggs. He said CT scan would be the most telling but it is $5k, ugh.
Some background info: we have a heat lamp and UVB lamp, no swollen eyes, no nasal discharge, Muddy had a big bowel movement on 7/13 during the drive to the vet. Muddy is 1.27kg, ~5.5 inches in length. We do not notice any weight loss, but I'm sure there will be since she did not eat today.
I would love some advice on what to do, and if there are any insight to what might be wrong with my Muddy?
I will continue the antibiotics for now (wonder if I should stop at any given point if there's no improvement?) but it worries me that she didn't eat at all for the first time in like 23 years. I feel like taking her to another vet for a second opinion.