When your gluteus maximus, medius and minimus are not both stretched and strengthened, pain results. When you sit all day long (and pretty much all of us do) these muscles become weaker and shorter.
Keep your Butt Moving!
Your gluteus maximus is the ‘primary mover’ for your hip let alone your entire body. If you’re not using it enough, you will hurt. The problem too is that the less you use your g.max. the more strained and sore it itself becomes.
Weak and sore glutes fail to support the lumbar spine leading to back pain. When they become tight, your pelvic tilt goes off and you easily risk injury to the discs in your back. It is important for you to start reconditioning these muscles to recover from pain.