Low back pain & psoas

I have a client who has chronic back pain that worsens
with rest and gets better with movement. It is
difficult for him to feel any sort of quad stretch no
matter how deep he goes and it seems that when I
instruct him to use his psoas instead of the quads to
flex his hip it is very difficult. He can access the
muscle, but it is a lot of work for him to use it -
even in a simple Vinyasa like Apanasana. I assumed
the psoas was weak and that was the cause of his low
back pain, however he stands with his feet in a
greater than normal external rotation, which also
leads me to believe that his external rotators are
tight. Can the psoas still be weak if the rotators are tight? Thank you for your assistance. Namaste, M

Has he had a medical diagnosis? IS he in psychotherapy? What is his major stress in life currently? Sounds to me like he is dealing with or rather avoiding deep seated emotional pain.

Did you check his knee flexion ROM? That will tell us if he really needs to do quad stretch. If heel goes to hip then no need for it. With standing in turn out his internal hip rotators are likely weak, external are likely strong. You need to Muscle Test (MT) to be sure. Can you do that? Test all concerned muscles - gluteus maximus, medius, psoas, hamstrings too