Pressure build-up on knee when legs are flat

I was stretching the calves the other day with one foot against the wall and leaning forward and could feel a lot of pressure on my knee, but for some stubborn reason I held the stretch. It sort of felt like something was about to pop out of place. Now a few days later I am sitting on my bed, legs flat typing this and it feels like a lot of pressure in the knee, almost like my knees aren't properly held together. My knees have been a bit sore for the past few days. I went the gym today and done a leg workout, which probably wasn't a good idea and the knee feels even more sore. Is it possible I have knocked something out of place?

suppose, it's better to give your knee a rest and maybe in a week to repeat your gym-experiment