Piriformis syndrome is a condition in which the piriformis muscle, located in the buttock region, spasms and causes buttock pain. The piriformis muscle can also irritate the nearby sciatic nerve and cause pain, numbness and tingling along the back of the leg and into the foot (similar to sciatic pain).
A common cause of sacral and lower back pain is trigger points in the gluteus medius muscle. This muscle is located in the hip and is responsible for abduction and stabilization of the hip and pelvis. This muscle often harbors trigger points. These knots will often refer pain into the sacrum and lower back area