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.
Diagnosis of flank pain involves medical consultation with a very detailed history of the symptoms after which the doctor may order diagnostic testing, such as blood tests, urinalysis or imaging scans, explains Healthline. Types of imaging that may be necessary include ultrasound, X-ray or CT scan. These are especially important if the doctor suspects kidney stones, due to the possibility of obstruction, but they also act as helpful diagnostic tools for medical problems in other organs, muscles or bones.
The primary treatment for any type of flank pain is rest, says Healthline. Other treatment depends on the cause of the pain. For inflammation, treatment may involve anti-inflammatory medicine, physical therapy or exercise. Antibiotics are a necessary part of treatment for pain due to infection. Kidney pain or kidney stones may require hospitalization, intravenous antibiotics or surgery.