Take care of your knees, people! I've had a dislocated left patella for about 8yrs. now, and it is crippling. I plan on FINALLY having surgery on it this coming winter, but if I had any means of paying for the procedure back then, and with some foresight, I wouldn't have hesitated as I have done.
Loony, sounds like maybe some compression-related stress injury, or the start of something of the like? I've never been totally sure how good steady running is for you. Cardio, yes..... leg joints, eh..... maybe.
Just my opinions, guys.