Looking at causes:
Core misalignments are most likely contributing to issues in these tissues. Common culprits are:
high iliac crest
pelvic rotations
In addition to treating the tissue, core misalignments should be addressed.
Stretching the tissue can be introduced on subsequent sessions provided that the symptoms are way down,
Below is a stretch that gets the abductors of the hip; quadratus lumborum and latissimus dorsi/teres major.