knee pain

Hi! I was a combat soldier and was into some serious running. In 1997, I met with a motorbike accident and had a soft tissue injury of the knee which subsided with pain killers. Now with my reduced physical fitness levels, I am suffering from pain in the knee after exertion ( a few km of walk)which extends to the back of my knee. I am also suffering from pain in the middle of my left foot( something akin to a fallen arch). Need advise. I do not want to think of surgery as an option at this stage, I'm 34.