I'm no doctor and I'm sure it presents differently for some people but I developed it last summer/fall and it was most definitely under or sometimes behind the kneecap.
Mine was fairly mild and the PT had me do a lot of stretching, like everyday for 2 months before I noticed a big difference(foam roller helps), and strength training to fix my hamstring/quad imbalance. What really got rid of it for good was when I got serious about strength training this summer in preparation for hunting season and ski season. When my hamstrings started to catch up with my quads in terms of strength I saw big improvements, to the point that I could forget to stretch for a week or two and not even notice. YMMV
"They don't think it be like it is, but it do."
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