I looked up trigger points and found this:
Posterior Knee Pain:
http://www.realbodywork.com/learn/knee/hamstrings.htm
Anterior Knee Pain:
http://www.realbodywork.com/learn/knee/rectfem.htm
The X is where the massage needs to be done and in red is the area that ache. Hopefully that helped. I was actually massaging the wrong area and I found this site and massaged the right area on the posterior side, and no aching right now. =) On that site, it has all the trigger points for all the muscles on there. Wherever you are tight, look it up on where the trigger point is.