lethargy but no fever

my 2 year old-ish kitty corrina is not feeling well. :'( less than two months, she got sick; lethargic and not very responsive to stimulii. i believe she was still eating and drinking, at least a little, b/c she would use her little box, but could barely get inside; more often than not, the urine ended up running down the front of the box. i took her to the vet, they ran all sorts of tests, all which came back negative. the levels in her blood and such were normal, although the doctor said some proteins relating to the kidneys were a little off, but that may have been b/c her kidneys were a little small. an xray showed her kidneys were a little smaller than what they should be. she did have a fever though, about 105. they put succutaneous fluid in her back, and gave me some antibiotics. about a week later and another fluid deposit, she showed signs of improvement. two weeks later, she was back to normal.

day before yesterday i noticed her acting strange again. lethargic, not very responsive. she doesn't seem to be running a fever, her ears are cool to the touch. her third eyelid is partially exposed. she responds when i get close (she meows) and doesnt seem to be in pain when i poke at her. she used her litter box today, and it didnt smell weird or seem bloody. feces also look normal. i don't know what to do. i don't want to take her to the vet and stress her out unnecessarily, especially since they didn't find anything wrong last time, but i can't stand to see her like this. any thoughts/suggestions?

Unfortunately, the stress of a vet visit is probably better than any advice we could provide. If the vet you're currently seeing doesn't want to dig to discover the source of the problem, then you may want to consider taking her (with the records) to get a second opinion from a new vet. So often they just have a bug that responds to antibiotics - but apparently there's something else going on with your baby. Until you take her back, they won't know they need to go looking for whatever it is.

went to the vet today - no immediate signs of whats wrong. kitten has lost weight though. =''( when i took her in months ago when she was healthy, she weighed 9 pounds. now she's 7 pounds 11 ounces. she seemed a little perkier today, but not by much. she has an antibiotic; so i get to forcefeed her meds AND food. :/

I'm sorry to hear she's lost so much weight - but it seems it was over some time. We've had that happen with one of our kitties.

I hope she responds to the meds! And if you have trouble force feeding her, did you discuss an appetite stimulant with the vet?