What Causes Severe Pain In Back Radiating To Buttocks?

I am currently taking oxycicone 5 mg every 8 hours as needed for pain due to scoliosis, arthritis, disc degeneration and a herniated disc in my lower lumbar area. This morning I awoke with a new pain in my back in the middle of my left side about half way down and it seems to be getting worse as the day progresses even though I m under the medication. I m concered if it could possibly be caused by some internal organ. I have never had this particular pain before and am concerned as to what might be causing it. I will be calling my internist in the morning, but in the meantime I am still concerned and what to do if it continues to get worse. I am completely puzzled. Is this something I need to be worried about or just try to hang in until tomorrow morning. Thank you for any advice you might have.