Good choice. I’m a big fan of Sripat. (Had and operation there). Most of their doctors teach at CM University so you should be in good hands.
To your present problem, I’ve had the same symptoms as you describe. My solution was to do the Glute Bridge excercise. That really makes your glutes work and strengthen. In less than a week the pain was gone. Since I don’t know what caused my pain and you still don’t know what causes yours, this exercise may work or not. Worth a try?