Weak glute causing tight quadratus lumborum and abdominal pain

Hi. I have a significantly weaker right leg due to an old knee injury (now healed). The glute that side is particularly weak.

I have been directed by physio to strengthen with single leg bridges, clams, adductors and extensions. Also stretches to the quads.

Been doing this for approx 12 months with gym work, but still find that my QL muscle on the same side tenses up when I put any strain/weight that side.

This causes me some pain and radiates to a painful point in my abdominal muscles (same side close to navel). This can only be remedied by laying down and resting.

Pressing trigger point on abdomen and massage of QL with tennis ball seems to work too.

Been dealing with this for 3 years and would really appreciate a breakthrough! Does anyone have any thoughts on what to do?