I have pain in my lower left side of my back, it started with bad lower back pain, now it's centered on left lower side.

Back pain: The most common causes of pain in this area is inflammation of the sacroiliac joint. Also, an inflamed facet joint in the lumbar spine or the sacrospinous ligament can cause this pain. Kidney stones can be a source of pain too. Begin with anti-inflammatory medications and apply ice to the affected area. If the pain persists then see a medical doctor.

Could be a number of: various causes, including sacroiliac joint pain, piriformis spasms, strains of various lumbar muscles & ligaments, intervertebral disk problems, myfascial pain & others. See your doctor or physiatrist for proper evaluation and treatment based on specific diagnosis. If a specific diagnosis is not made, see a physiatrist or other spine specialist. There are many good ones in your area. Best wishes!