Hi Hope this might help? Personally I don't have knee issues or experience pain so I don't really know how to guide you apart from maybe identifying possible bad form? ( Not saying bad form is the reason, I mean you can just have bad knees which would suck)
1. Weight on the toes: This happens a lot when using too much weight which tends to pull your body too far forward. Other times it’s simply a lack of awareness of how to distribute one’s body weight.
2. Hips & knees move forward while squatting: This is a huge reason most people’s knees hurt squatting and an example of poor movement mechanics and/or tight hamstrings.
3. Thighs and lower back muscles doing most of the work: This happens when the core, glutes and hamstrings are weak. When you lack proper core and hip strength muscle imbalances often result in the quadriceps and lower back over working. This is one of the main reasons for knee pain during squatting.
4. Abs and hips are weak: These muscles need to be properly strengthened in order to eliminate knee and lower back pain.
5. Trunk collapses forward: This is a sure-fire sign of weak abs and glutes.
It’s important to understand that each of the above are caused by muscle imbalances that cause pain and injuries to areas of the body like the knees, back, shoulders, neck, ankles and feet. In other words, movements like squatting and lunging are not bad for your knees and they don’t cause injuries. Muscle imbalances are the real problem. If you don’t address muscle imbalances your knees hurt squatting, lunging, running and your pain will get worse over time.
http://www.menshealth.com/fitness/why-s ... ke-it-stop
http://functionaltrainingcoach.com/why- ... orrect-it/