Lower back pain that originates in the buttock area is usually sciatic nerve related. It is triggered by many different things including: high heels, sitting on a wallet, standing in one place or sitting too long, recliner chairs, crossing your legs, and unaccustomed exercise or activity.  Treatments that work to help allegiave the problem are:  Reflexology, Chiropractic adjustments, massage, homeopathic remedies sometime help.  An old home remedie is to soak your feet in apple cider vinegar. (haven't tried this one).  Exercises that help are to lay flat on your back and bring your knees toward your chest several times.  Sleeping with a pillow between your knees also helps.