the piriformis muscle is caused by sports activities
such as soccer, tennis, handball, basketball when there is a quick change of direction. When not well conditioned , vulnerable muscles like the piriformis are the first to suffer. So does inactivity such as sitting too much, can promote the development of these trigger points.
I can help you with the right therapy to open this muscle that is swollen and shortened.
In addition this tight muscle affect the the pudendal nerve which affects all the groin area too.