I saw a posting on the Runner's World forums that contained a great quote from "Lore Of Running" by Dr. Timothy Noakes:
"Never accept as a final opinion the advice of a non-runner."
When I first started running (15+ years ago) I developed a pain in my ankle which I later learned was tendonitis. My doctor's recommendation: "Stop running for 3 weeks. If the pain returns when you begin running again you weren't meant to run and you'll need to stop for good." I rested, started again, and the pain returned. I figured the doc was the doc and my short running career was done. Then I started to read about foot types.....and shoe types......and pronation.....and motion control shoes..........
I went to a good running store, bought shoes appropriate for my feet, and I was running pain free! My doc, obviously, knew nothing of these topics.