My sacrum has recently started “flipping” into an awkward rotation causing the entire pelvic bowl to sort of twist (if that makes any sense?!) and thusly creating some major imbalances, muscle spasms, etc etc… Its as if you held me by the hips (illiacus) and tipped one side down (anterior side rotates inferior, posterior rotates superior) while tilting the opposite side up (anterior side rotates superior, posterior goes inferior). I have been a comprehensively trained Pilates instructor, professional dancer & teacher trainer for many many years so I have tapped into all of my experience and resources, yet still having the recurring problem. Have been working with a massage therapist 1x week to get through the fascia and loosen the sacrum to get movement/bloodflow back into pelvis, but still… I am desperately seeking corrective exercises to help me stabilize this wonky pelvis!!!
I looked at your profile and noticed that you are a trained dancer and many of the formats that you teach are related to ballet. I’ve noticed that many classically trained dancers are able to extend their limbs outside of the normal range of motion and often need to develop stability around a joint during the eccentric phase of muscle contraction. It is possible that this might be causing the instability. Hyperflexibility can cause hypermobility of joints and in your case it is the sacroilliac joint. There should be very little movement there. In my experience, I have found more people who need to learn corrective exercise to loosen up a tight SI joint, as opposed to a hyperflexible SI joint.
As we are both pilates instructors, I am sure you would agree that it is difficult to suggest what corrective exercises would be helpful to you without performing a movement screen. Afterall, in pilates world, a movement screen is the basis upon which we design individualized pilates programs.
I thought as you are certified through Power Pilates, I might suggest that you shoot an email to the president of the organization that you are certified through, Dr. Howard Sichel. I am sure you are aware of his credentials. Other than, perhaps it is time to see your doctor.
Hope this is of help to you and I wish you well soon.