RVC can be sign of dysmetabolic neuropathy, because Crystals of salt can hurt glomerules. White blood cells will indicate infection. You told nothing about protein in urine, which also indicate infection more often in glomerules. We need additional urine analysis-cytology, analysis for salts and other. You should consult at nephrologist. For treatment infection better use cefixime,because it is very sensitive to E.coli, which causes inflammation in kidney. Give to baby plenty of water. Recovery soon