I have few main problems with squatting:
Butt-wink. I know it’s caused by tight upper hamstrings, but i can’t stretch because i just don’t feel them stretching. I’ve tried foam rolling, but it didn’t helped too.
Knee pain. Sometimes i feel it, sometimes not. Usually it’s gone on last few sets. I believe that it’s caused by tight leg or hip muscles, but I’m not sure which ones.
So, could anyone help me here?
I think that butt wink has more to do with adductors than hamstrings. The hamstrings cross the knee so in deep knee flexion like the bottom of a squat, they aren’t maximally stretched. Alternately, you may just need to play around with different foot placements and toe angles to find what is right for you.
As far as knee pain, it can be caused by tightness in certain heads of the quads. Also, you might be having some knee valgus, which could be caused by tight hips (adductors again, perhaps). However, knee valgus is more complicated than that since many people can look fine in the bottom position and then only have valgus as they go up.
What worked for me was ULTRA wide squats (no weight). Like mega wide, just go as low as you can, push your knees out with your elbows and hang out there, you’re supposed to feel like death in your ADDuctors. This will ultimately open up your hip flexibility which is a reason for butt wink (don’t quote me on that). Since I’ve been doing that (and other hip flexibility exercises) my butt wink has decreased significantly. Also keep your back as tight as possible.
For your knee pain there are a bazillion reasons why you might have it. Play around with stance and foot placement like Silyak said and also bar placement because your knees might be able to handle one center of gravity, but not another.
Also check out this vid it might help you because femoral erector tightness is a factor in knee pain:
