Your pain is changed by more than just what’s going on in your knee.
Pain is also changed by things elsewhere in your body and elsewhere in your life.
The brain makes knee pain when all the information it has says that the knee needs protection. This includes what you're doing, what you're thinking, and how you're feeling. It also includes what's happened in the past, and what you expect to happen.
When you are angry, worried, feeling down, stressed, tired, or sleeping poorly, the knee problem seems worse. So, you get more pain. This does not mean that your knee is more damaged.
You do not have direct control over your brain making more or less knee pain. If you realise why this happens, you can change how you view and react to these changes in pain. This way, the pain may have less effect on you and your life.