Do what Starrett call informed freestyling for all the aspects of the muscles in your hip.... glutes, hip flexors, abductors, adductors, etc.
You'll usulaly find tight spots and for SI joint problems you'll usually find some stuff that's not the same on either side.
That should fix the problems if you can locate the tight spots.
Also consider using lacrosse ball or golf ball and rolling teh whole gluteal region from the sacrum area (especially along there) to the hip, glute medius and TFL. That tends to hit everything even the deep hip external rotators