The two primary symptoms of pyelonephritis are pain in one flank, the area just beneath the lower ribs in the back, and fever. The pain can travel around the side toward the lower abdomen. There also can be shaking chills and nausea and vomiting. The urine may be cloudy, tinged with blood or unusually strong or foul-smelling. You may need to urinate more often than normal and urinating may be painful or uncomfortable.