What Are Some Causes of Left-Sided Back Pain Above the Waist?

Possible causes of left-sided back pain include kidney stones or other kidney disorders, urinary obstruction and rib cartilage inflammation, according to Healthline. The pain may be achy and cramp-like, or it may come and go in waves. Constant or severe pain in the flank can indicate a serious medical problem. If symptoms also include nausea, vomiting, fever, chills, or bloody urine or stool, the patient should seek prompt medical attention.