3. Left frontal hip pain and possible SI joint dysfunction
might be posterior capsule dysfunction.
spine position and flex knee and you feel restriction and pain in the front of hip joints.
possible cause is posterior capsule become adhesive or structures attaching to illium become scars, and change the axis of rotation. it then crash into where it is not supposed to do.
or worse case, labrum tear. (in which case Wikipedia reference-linkMRI does not show in your case)
can you compare right and left? it has to be done by passive at the end range for joint play.

MRI or other imaging cost more and sometime it wont show the dysfunction in hip joints.
so treatment of posterior capsule by myfacia release or active release technique or functional range release is recommended for left side. or external rotators stretch such as this can reduce pains.


"I have pain where my thigh meets my pelvis and I haven't been able to squat for nearly 6 months right now because of the crippling pain. I made the mistake of squatting through the pain and aggressively stretching before hand, yeah ... that didn't work out too well. It got to the point where even breaking at my hips would make it feel my entire pelvis was about to crumble. It's better now but that isn't saying much."

A month or two ago this pain popped up in and around my ass.

which side is the pain side? is it the same side as frontal hip side? if it is the same side, it might be caused by compensation from our frontal pains.
since your body does not want to hip flexion, hamstrings become so tight and cause pain.

can you do simple muscle testing by yourself to replicate pains?
do hamstrings muscle test.
Sit in straight position and grab symptomatic side of leg around ankle and push toward your body and you resist that movement away from your body.
change the angle of knee from 90 degree toward 180 degree.
if that replicate the symptom(pain on ass), it is likely that hamstrings or junction between gluteus max and hamstrings are adhesive.
you might have referred pain on ass from dysfunction of frontal hip.

I love to see how you squat, flex hip(spine) and , standing lumbopelvic flextion, extension, and rotations.

the way to do standing lumbo[pelvic flextion
standing, and flex from your pelvis and try to reach floors. then also do by isolating right and left. place something like 7-8 cm books underneath of your foot and your leg(on books) should be slightly bending. then try to reach on the floor. Which legs(legs not on books) show restriction in flextion? is there any pain? if so where it is?
is it the same spot as you squat?


by the way have you done any eccentric exercise for this problem? if so how often and how long(months) and what kind of structure (location, name of muscles tendons) are aimed

If there is not caused by dysfunction that requires surgery, there can be a solution. hang in there.