Compact set chemistry

How can I get back into running and over my knee pain? - back of knee pain more condition_symptoms

A couple of months and I'm knee injury when I came back, I was back to normal operation, running and cycling. Recently, a few weeks but I am sick and stopped the practice. Well, my knee hurts more than ever before, when I tried to go there. Even walking is fast pain. What must I do to get fit and to be running?