First back off and deload a little to let them recover a bit. I'd simply build up volume squatting starting back at a moderate weight and maybe add in a lighter, higher rep backdown set after the main sets. The other thing that you really should do is simply stretch them while you're warming up. Just do a bodyweight squat and use your forearms to push the knees out while keeping your back straight (not rounded). also make sure to stretch your ankles out prior to squatting so the ankles don't cause you to pronate and collapse the knees either.