So I've been squatting since January or so, and over the last two months, I've continually injured myself when performing the movement. Basically, if I squat sufficiently deep (to parallel), I get a pain on the left side of my leg. This pain is right at the top of my leg, where it joins with my torso.
When this happens, I'll lay off squats for around two weeks, and when I come back, the pain is gone at first. However, by about the 4th set of a 5x5, the pain comes back. This pain doesn't occur when I squat above parallel.
In the meantime, I'm now doing leg extensions as a substitute, but I'd like to get back to squatting if possible. Any ideas about what might be wrong?