Thanks. My injury didn't seem to come from running - it happened from me squatting down at home, so it was an instant thing unrelated to my training as far as I can tell. I've not had any issue with my knee up until then, never had any bad feelings in it etc - seemed fit and healthy. I am also in my early 20s.

The thing which makes me question whether it is cartilage damage is that I didn't have this knee clicking feeling (or knee unsmoothness) when I first injured it. I started to feel this about a week after, and at the same time I noticed a strange texture at the side of my quad muscle - it was like a bubbly or netty texture just over the muscle (maybe the muscle fascia?), and it went into the joint where I couldn't get to it with my fingers. It disppeaered from the muscle when I rubbed it for a minute or so. Does anyone knoe what this could have been? If any of that texture is around/under my knee cap then I am pretty sure it would cause the issue of the knee not being smooth and also the clicking? I mention this because I felt the same texture today after I have been jogging.

Any help would be great, thanks