Many people have problems doing the squat because of different types of pains, and also because of different mobility and flexibility issues. This is usually because of deep structural problems and imbalances in the body due to our sitting lifestyle. This often also causes us a lot of pain as well, for example back pain and can limit our mobility.
Two very common problems among people who sit on their ass all day are tight hip flexors and tight hamstrings. Here are some exercises to help you get rid of those:
Here are some good stretches to get rid of those tight hip flexors:
Foam rolling is also a great exercise to help stretch the different areas of the body that are tight, for example the hamstrings:
If you do these at least 3 times a week, then you should feel some relief very soon. This will also help you with your squat form and allow you to lift heavier weights.