Pain in right hip on flexion and contraction

I've been experiencing pain in my right hip flexor area when I lift my knee towards my chest in flexion and when the muscle has to contract - for example, sometimes if I'm getting of the sofa, or I sneeze particularly violently - for 11-12 months. I'm currently seeing a sports therapist but she's somewhat stumped to the cause of the issue, so I'm trying to seek some additional assistance to help narrow down the cause and therefore treat it effectively.

From my own research I've worked out the pain is coming from the underside or underneath the top of my sartorius muscle when I bring my hip into flexion - it's just below the end of my inguinal crease and most definitely in line with/underneath the sartorius as that pops up when I flex my leg and abduct it slightly. Edited to add, I think the ‘epicentre’ of the pain is about 1-2” below the crease if you follow the sartorius muscle downward.

I also get a 'clunking' about 90% of the time if I do hip rotations on that side - something I think from reading is likely internal snapping hip syndrome? I should note that this in itself is not painful although I do feel a pain from the sartorius area when bringing my knee up towards my chest. I've also been checked out for inguinal hernia and my GP couldn't find any evidence (and I've carefully felt around the whole area myself and can find no evidence of lumps). I had an MRI done on my back and hips 14 months ago and there was no evidence of any issues (full report copied below main body) and as this pain started approximately 2-3 months after that MRI was done, I'm fairly confident the issue isn't related to the joint itself.

I've self tested for the Ludloff sign as well as resisted and passive seated flexion and whilst there is a bit of tightness in the Ludloff test and it's much more difficult lifting the affected leg than my good one, the pain is more pronounced if I ring my knee up past 90 degrees (both passively but especially if resisted) when my knee is flexed in a normal seated position.

Is it possibly that the issue could be stemming from the iliopsoas tendon/bursa and would the pain be pronounced in the area I'm feeling it (and only on flexion), or is it more likely that it is in fact coming from my sartorius muscle? Does the outcome of the Ludloff test make an iliopsoas problem less likely?

Thanks for reading and any advice offered.


Hip MRI results:
"Both sides have been scanned and comparison is made.There is no cam appearance.
No femoroacetabular impingement.
The femoral head neck junction is well preserved.
The adductor origin is normal from the pubic symphysis.
The hamstrings are normal in appearance posteriorly.

The greater and lesser trochanters are normal in appearance and there is no evidence of
trochanteric bursitis.
The SI joints are normal in appearance

Conclusion:
The femoral head neck junction is normal in appearance. There is no evidence of a cam
appearance. There is no femoroacetabular impingement seen.
No joint effusion seen.
No bony oedema seen."