re not orthopedic surgeons, unfortunately. From
my own experience with a bad knee
, this sounds more like either tendon or cartilage problem rather than muscular, if it is in fact in the knee. That's a joint, not a muscle. If you hurt muscle doing squats, it would most likely be in the glutes or the thighs or possibly the periformis, and it would probably just be sore, not injured unless what you don't say is you were doing this exercise with heavy weights.