Hip Flexor Pain Out of the Hole During Squats

I have been doing Starting Strength for a while now. I have been squatting rippetoe’s low bar style.
The pain started small, a tinge of pain in my left hip flexor, and was only while squatting for a week or two, but then it started hurting after the workout as well. Now if I squat my left hip flexor will be slightly numb (or something) halfway down the leg. I took a week off of squatting, but decided to try it again today, because I’m a young guy, and usually heal pretty quick. The pain came back.

I researched and it looks like hip impingement could be the issue, which would explain the pain happening only once i get to the bottom, and maybe numbness. I am hoping that instead, its a leg strength imbalance issue. I had surgery on my shoulder last year so I have slightly less mobility in my right shoulder and the bar rests slightly unevenly on my shoulders.

Alternatively, it could be shitty form (most likely lack of hamstring engagement), but I honestly think that it isn’t very bad.

Hope i didn’t forget anything.

it could be anterior femoral glide. does it pinch if you push the femur back into the socket with your hand as you squat? (try that without weight). how about if you do quadruped rocking? it could be due to your lateral rotators / glute max not kicking in properly on your squats (your hamstrings don’t work as well to position the femur in the socket properly). perhaps.