Your piriformis muscle can be a pain in the butt. Literally.
It can cause issues such as sciatic nerve symptoms (that pain in your backside that may run down your leg) as well as providing you with a functional leg length difference or pelvic dysfunction.
And as for that pain in your shoulder? Well that may well be due to the piriformis too. If the muscle is in spasm it can cause other areas to compensate including your upper back and shoulders.
Think about it. If you have tried fixing your shoulder by working on your shoulder and it hasn't worked, then maybe, just maybe, the issue isn't your shoulder.
This Muscle Energy Technique increase the mobility in your piriformis muscles. Tightness in the piriformis can also cause pain or injuries in the hip, lower back or knee so it is important that you try and keep them moving freely.
Sit firmly on a chair and lift one knee towards your chest. Place both hands behind the lower thigh then press your thigh down into your hands (as if you were straightening your leg out). Press at a comfortable resistance (~20% resistance to start). Make sure your leg does not move and that you relax your head and shoulders. Hold for 10-20 seconds. Release and repeat 2-4 times on each leg. Repeat 2-4 times a day. You can also perform this lying.
If something doesn't feel right then don't do it. Mobilising restricted tissue can be uncomfortable but it should not be unbearable. PLEASE use common sense!
This is NOT medical advice and is used for educational purposes only. If you are having pain or health related issues, please visit a healthcare professional.