A kidney problem, such as an injured, infected or inflamed kidney, causes a dull ache on one side of the upper back, according to Mayo Clinic. Fever and urinary symptoms may accompany the pain. Kidney stones can cause sharp waves of intense pain when they move out of the kidneys.
Hemorrhages, infarctions, tumors and cancer commonly cause dull kidney pain, according to University of Pittsburgh Medical Center. Sudden, severe kidney pain could be a sign of a hemorrhage or blood clot, and it requires immediate medical attention, whether or not there is blood in the urine. The kidneys are positioned below the ribs, which is why patients experience kidney pain in the upper back or side.