You know when you do a full squat and you can bounce up at the bottom? Is that ok? cuz my knees are hurting and grinding lately.
As with most any other lift (power/Olympic lifts excluded), when you are bouncing you are cheating the exercise. Essentially you are forcing your connective tissue take over the majority of the load, work that you should be forcing your muscles to do in order to work them to exhaustion, properly through a whole movement. Your ligaments and tendons get plenty of exposure to exercise when done properly, and bouncing like that is only going to end up doing a lot more harm then good.
It is not a good thing to place that kind of strain on your need joint. The joint, while capable of coping with that kind of stress on a limited basis, was not meant to do so on a regular basis, especially with the added weight. It is very likely that this is part of the reason your knees are hurting you right now.
Your best bet is to give your knees some time off, along the lines of a week or two. And that doesn't mean moving to extension/flexion machines, they can often be pretty hard on the knees as well. If you plan on continuing to work your legs, do so with slow, controlled knee bend squats or lunges with less weight until your knees are feeling better on a permanent basis. After that, maintain a better squatting form, limiting yourself to a slow, controlled knee bend that does rely on a bounce.