Hmmm I know the pain very very very well, I have popped my knee cap out fully about 8 times now and multiple times it trying to give out on me and having to straighten the leg quickly to prevent it going out. Anyway recently I decided enough was enough and was meant to be having a Cat scan today, anyway for various reason the Cat scan never happened today So the specialist is booking me in once again for another!
Feeling the pain dude as one time I swung out of bed in the morning and my knee went out and the pain was that bad I was retching in the loo, bad times!