<human>: 3 weeks ago my husband and I put down vinyl plank floors in our house, over the course of 4 days. Most of that time I was down on my knees on concrete slab and thought I was tough enough to not use kneepads. During and since that time, I have had major trouble with my knees. If I bend my knees more than 90 degrees, especially when weight bearing, I have intense pain behind the knees toward the outside. If I continue to bend like I am getting down on my knees, the pain then wraps around under my kneecaps and is extremely painful. Anyone have thoughts? How long before I can exercise again?

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<bot>: Pain behind knees starts on the outside and goes behind the kneecaps when I bend the knees while weightbearing. What is this?