Joint, bursa, tendon
Even though the knee is a joint, there are a lot of other musculoskeletal structures around it that can cause the pain.
In your setting you need an evaluation. Do the joints swell? Are they better or worse after exercise
? Are you stiff in the morning in the knees? Elsewhere? Do you have other medical problems? Rash
? Fevers? Chest problems? Stomach problems
? We look for these to diagnose.