This gives you a pain in the bum… usually a deep in the buttock and is often accompanied with sciatica type pain as well as other issues like restless leg and low back pain.
The piriformis is a deep muscle which attaches from the sacrum in the pelvis to the outside of the hip joint. In many of us, the sciatic nerve passes through the muscle. In others, it passes alongside it. When the muscle gets tight it irritates the nerve and hence you get the symptoms. The reason the muscle gets tight is mostly due to the Sacro-iliac joint becoming dysfunctional.
A full assessment to find the cause of the recurrent tightness as well as treating the tightness with manual therapy and stretching is the treatment of choice. Sometimes treatments like acupuncture can be very helpful when the muscle and nerve are particularly irritated.