This confused me. Do you even have a knee problem? If you do they can put you to sleep and fix it. On a weirder note this is extremly common in dogs and they fix it all the time. If you are scared of pain they can make it so you do not feel any pain. Twilight sleep so no worry there. If you dont you have ocd and need to see a psychiatrist for it.
It sounds like one of the many symptoms of anxiety....worrying about something without reason. That is what anxiety does. Have your doctor check you for anxiety, Honey.
Classic symptoms of anxiety. Anxiety makes ideas race over and over in our minds and we are literally on the end.
Yes, get these feelings off your chest, its a good thing. I too have racing thoughts. I meditate but sometimes the anxiety wins and sometimes it doesn't.
Have you talked to your doctor about your anxiety? If not, that maybe a good start.