Hi, I am afraid an infection of the kidney mild not actually be classified as mild, and taking an anti biotic for 3 days might be insufficient. The kidney is a noble organ of the body. A specific diagnosis and appropriate treatment of kidney diseases is compelling. In proper contexts, a presumed kidney infection should ideally be accompanied by a urine culture and sensitivity tests to decide on the appropriate anti biotic. Persistence of symptoms as you describe might deserve a more invasive watch and maybe an abdominal ultrasound. Kidney function tests could also be worth performing to ascertain actual level and function of the kidneys. Persistence of symptoms might warrant booking a visit with the nephrologist for a proper evaluation. While waiting, complying with the antibiotic plan and drinking a lot of water could be helpful. Hope this helps as I wish you the best, Thanks and best regards, Luchuo, MD.