If pain shoots down from your lower back, through your bottom, and into your leg, the culprit may be your sciatic nerve. A herniated disk, bone spur, or some other spine problem can put pressure on it. Doctors call this sciatica. It usually affects only one side of your body. Hot packs, cold packs, stretching, and painkillers can help you feel better, but you may need a doctor to fix the cause.