Day 3 of antibiotics for kidney infection right side still hurts as bad and left starting to hurt but not as bad as right could infection spread?

See answer. It can take a good 3-4 days of antibiotic therapy, fluids, and rest before one begins to feel better from a kidney infection. Persistent fever (>100.5) or worsening of symptoms would begin to be a cause for concern. Important then to make sure pt on appropriate antibiotics (recheck urines culture) and to make sure no abnormalities of kidneys (renal ultrasound or ct scan imaging).