Sorry for double posting again, just thought I'd post another update.

A minute ago, I was feeling along the inside of my knee where some of the pain is coming from. I felt a lump just floating about in my knee. It felt rough and gristle-like. As I was trying to feel it, it moved and now I cannot feel it again. Is it possible this is a bit of loose cartilage?

Also, I've noticed that, as well as my knee cap grinding against my tibia, if I tab the knee-cap towards the back of the knee, it knocks against something. I'm slightly concerned about the 'looseness' of my knee cap.