Knee complaint

I have a knee problem that has been restricting me for a few weeks now. I have experienced some soreness in the outer sode of my right knee. The pain is not severe, more like an ache. It is becoming a nuicance. My chiro thinks it could be due to hamstring tendonitis or a tight calf muscle, but is not sure. He suggested I could strengthen my VMO.

The movement that triggers the pain is rotating the toes outward when the knee is bent at 90 degrees.

What is this likely to be, and what should I do?