It's a made up word. It sounds like arthritis of the knee is what's going on. However, there is no such medical term as "kneeitis"!
"Kneeitis" is not a recognized medical term. It may be a colloquial or slang term referring to pain, inflammation, or irritation in the knee joint. It is important to consult a healthcare professional for a proper diagnosis and treatment if you are experiencing knee pain or issues.