Hello @EssCee,
Without seeing an actual video or im age of you squatting it is really hard to determine what you could be doing wrong.
- If you have pain in the knee, this can come from your knees collapsing inwards instead of going outwards.
- It could be because the angle of your shins is in a wrong position for your body composition (too much forward/too far over the knees or too straight/powerlifter style)
- The issue can also come from somewhere completely different, like a twist or misalignment in the hip or spine, leading to an uneven movement pattern.
- It could be the flexibility of your ankle joint not being flexible enough. The knee is rather a fold joint in the kinetic chain and driven by the movement of feet and hips, so these have a big influence on it.
- And it also could be that you don't place the weight correctly on your feet (Flat, and towards the outter rims) and weaken your movement and joint patterns.
- Foot position (are they slightly tilted outwards / about 30° max).
- The weight could be too heavy and you simply can't support the load and getting pain when trying to stemm this back up. (especially when the tendons are loaded with a weight the muscle may bare but the tendons had no chance to adapt to)
- Stopping / slowing down at a 90° angle and putting too much strain on the knees.
- Last but not least it could of course also be something with your knee you already had, or recently caused. And injury or defect you werent aware of.
You see there really is a lot that could go wrong. the usual top 3 are collapsing knees, incorrect foot placement and incorrect load on the food, and the ankle joint collapsing inwards or it's back / for tilt being incorrect.
Pay close attention to your form. Go in front of a mirror, take much less weight, and watch yourself to find out what could be wrong.
You can also upload a video here and i am sure everybody will be happy to give comments and thoughts on it.
PS: also when doing the ass to grass - make sure you just don't go until you touch the back of your lower legs, or until you already do the so called 'buttwink'. Make sure you only go as deep as right 'before' you start to do that wink with your butt. We all have different flexibility and we all have a different 'deepest' point in a squat. Which can of course increase with training and especially with mobility training.
Cheers!