Poor little one! Sounds like if he gave you KD he thinks the problem is in her kidneys.
Dogs do get fevers so not sure what your vet meant to say. One check for infections would be that bloodwork which should have white blood cells high if there was infection.
Its good that she urinated. Key thing is to keep her taking fluids.
If the vet gave you no diagnosis or treatment plan other than nursing you could let them know that the dog is not doing well or eating for you and see what the response is.
Alternatively you could get a copy of the testing already done and see another vet. Perhaps one who specializes in small animal internal medicine as they handle tricky cases all the time.
This site might help you find one as I listed above
http://www.acvim.org/Specialist/Search.aspx
There is an inherited kidney disease in the breed which you can read about here
http://www.lhasa-apso.org/health/hrd.htm
If your vet gave you no diagnosis, no home care info, no prognosis then you can ask about that over the phone and see what they say.
Please press Accept if you find my answer helpful. Want more info? Just reply on your question!
Bonuses for good work are always appreciated!
Thanks for the opportunity to help you!