Knee Pain | Kneecap Mobility Issue


I am writting because I have been having patellofemoral pain for three years - now I am 27 years old.
I have visited several doctors and physiotherapist as well, but they all could help moderately.
Basically: my knee pain comes up whenever I do e.g. squatting or even climbing stairs (the pain is not considerably).
Location of the pain: the pain radiates from under the kneecap.
1st deviation: my aching kneecap mobility is smaller than the other one’s.
2nd deviation: there is a major (at least 5 centimeters) difference in how close to my chest I can move my knee during the Knee to Chest exercise.

I think that my kneecap pain is because of my stiff tendons been around my kneecap.
I think also that my hip has an important role in my kneepain.

I would like to ask for your help because I have not been able to cope with my “jigsaw puzzle”.

Every comment is welcomed!