It's more than likely it will be a urinary tract infection, which is common with kidney disease, but your vet can confirm it. It needs treating. Antibiotics are not ideal in
kidney disease, but needs must.
Next, the red blood count is actually high, not low, according to my understanding. And this is very likely due to dehydration. This makes fluid therapy much more important. If I were you, I would ask about starting Sub-Q fluids at home.