In reply to verygneiss:
The thing is, people say they stretch and think that its a tick box exercise ie bending over touchingtheir toes and pulling their foot up to their bum and think thats it, 30secs job done.
Im my experience stretching can/should take me around 20mins and thats being quick but thorough both before and after running.
Ive had a knee problem for two years now. First trip to docs ended up with me having a cortozone(?) Injection which felt like it made it worse. I had an xray(possible floating bone?). Then had an MRI scan(cartilage damage?) All to no avail. The problem was something simple.
I had been running with 35lb pack training for paras10 race for afew months.(building weight and distance and in boots gradually!) Id neglected my stretching. As a result, my hips became tight, my IT band became rediculously tight and because the IT band was too tight it wasnt supporting my knee as it should so the front inner muscle was working overtime to try and counter it. Everytime i weighted my knee and bent it it would feel like a knife going in and would just give way.
I ended up finding all this out myself by reading books and talking to mates and was then backed up by a physio who gave me hell as she battered my IT band and surrounding areas till it was nice and buttery again :-D
The problem has gone and providing i keep my stretching routine up my knee is fine.
I hope you find out the cause quick and get it sorted!!