Here are some exercise Hip Stretches and
Piriformis
Stretches you can do to loosen the piriformis muscle and promote
rotation of
the hips.
The
piriformis is one of many small muscles of the body located deep within
the hip
and buttocks region. 
It connects the lower area of the spine to the top of the thigh bone and aids in external rotation of the hip joint.
There are many muscles and tendons that make up the hip and buttocks region.
The piriformis is the horizontal
muscle
running over the top of the sciatic nerve.
Start by lying flat on your back with your legs outstretched and your arms out wide. Now bend one knee and bring it up toward the body.
Grab the knee with opposite hand and force the knee diagonally up and in toward your body. You should feel a twinge within the gluteus muscle which should stretch out the Piriformis muscles. Hold this position for 10 seconds and repeat on the other side.
Begin facing forward on the ground with the arms straight above your head and legs in together. Now bend one leg and bring up, diagonally across the body. With your body weight lean backwards into your gluteus to effectively stretch and loosen out the piriformis.
Hold this position for 8-10 seconds and then switch leg to get full piriformis stretches.
Grab a towel or a tshirt for this piriformis stretch. Stand upright and hold this at two end a good bit wider than shoulder width apart. With the towel (or shirt) in this position, squat down below 90 degrees and then drive up through the heels.
While driving up you should really focus on the gluteus to engage the piriformis. Repaet this movement about 10 times. [Note: Hold the towel above your head right throughout the stretch]
The front leg swing indirectly stretch out the piriformis and also stretch out the hips. Ly Flat on your back with your arms outstretched and your legs together.
Now bring one leg across the body while keeping your back and arms on the ground. Hold this postion for 8-10 seconds and then do the same with the other leg.
These are similar to front leg swing only you ly face down and swing you legs backward. Remember to keep your hands and upper body in contact with the ground!