I have a mild disability and walk with my left knee slightly bent, as a result my kneecap has ridden up slightly and is slightly inwards. I have had pains in it since I was young that tend to come and go, but at the moment it is bothering me more so than usual. It hurts just underneath my kneecap slightly to the left, also swollen, and a little in the kneecap itself. The thing is, the pain isn't constant and doesn't always prevent me from doing things. It hurts and stiffens up whilst going downstairs, walking down inclined ground or walking for a period of time. I don't know whether it is worth getting it checked out or not because the pain is only dull, just quite frustrating.