Help - creatinine and BUN

Hi everyone,

My dogs appetite has decreased in a matter of days and he isn't eating at all without the help of appetite stimulate. I've been in and out of ER's and vets and they still can't find out what's wrong with my pup. I'm going tomorrow morning but wondering if anyone has dealt with something similar?

Creatinine levels is 2.2 BUN is 41

Urinalysis, protein and glucose are high but normal in blood sample.

Negative for lepto

They seem stumped, I'm panicking, I just want to know what's wrong with my baby.

Any insight is much appreciated!