Thank you for posting. I have several conflicting signs and now going to see a specialist in polymyositis (that actually treats this rare disorder) to see what possible subset. Very confusing and a two year journey.

My suggestion to you, is to maybe google lumbar instability because if the general muscles have weakened surrounding the spine, then your core muscles will be weak. One spinal doctor told me at the beginning of my journey to exercise core muscles to strengthen, never asking why these might be weakened.

I have not had a muscle biopsy yet but your information will help me know what to ask.