6 mos old with three day fever of 104, WBC 24000, all else normal. Urinalysis normal but dr still thinks its kidney infection. Possible? If not, what?

Wind/wound/water. In med school we were taught to look at the lungs/a wound/or the urine for the source of unexplained fever.In a 6mo girl i would consider a uti, less so for a boy but possible. The urine might be clear to initial look, but should show growth of any germ within 24 hrs.Stress can increase the WBC count & some viruses can produce high fevers for days.
Bacterial infecton. Such a high white blood count almost always indicates a bacterial infection. However, if there was a kidney infection i would expect the urinalysis to show some sign of it. So the question is where is the infection? It seems reasonable to do further testing. It is also reasonable to start antibiotic treatment, but it is ideal to know what type of infection is being treated!