I sure hope it gives you some relief Sephie! :) I usually just roll side to side slowly on the ball against the wall in the buttock area and look for tender points- or areas of pain. The piriformis muscle is in the mid-buttock area. If I find a tender point, I roll on and off of it a few times or press on it for a while until the pain lessens.
The foam roller you mentioned also helps me loads! You could also roll out on one of these to help the pain in your buttock. You may want to look up videos on Youtube or online as to how to go about
it, if you do decide to do it, as I find I always roll too hard!
I am always happy to share about
myofascial pain syndrome and trigger points as it is something I knew little about
and learning about
it changed my life! Apparently, the syndrome is quite common nowadays and is often overlooked.
Myofascial Pain Syndrome (MPS) also known as Chronic Myofascial Pain syndrome (CPS) occurs when the connective tissue around the muscles, nerves, etc. (known as the "fascia") becomes knotted- often due to doing repetitive movements without enough stretching. These knots, known as "trigger points", (or TrPs), can then cause the connective tissue to tighten up, causing pain, nerve pain (or sciatica, which can be like a burning sensation or electric shooting/ stabbing sensation- if the knots press on nerves), muscle spasms or twitches, limited mobility, etc.
Hope this helps! Any other questions, please fire away :)