No fever, and it doesn't appear to be swollen in comparison to the other knee. There is slight tenderness on the inside side of the knee cap and barely noticeable small puffiness on the outside side of the kneecap, but just barely. The pain is mostly in the muscle right above the kneecap.
As it has been 3 weeks since the pain started I would recommend that you get yourself examined by an orthopedist who shall be able to pinpoint the origin of your symptoms and order any relevant investigations.
I would be happy to answer any further queries you may have.
Most cases of quadriceps tendinitis resolve but may take few months for resolution of symptoms.