What Causes Sharp Hip Pain Radiating Down The Leg?

Yesterday I experienced, while sitting at my computer terminal, a sharp pain in my left hip and shooting right down to my left foot. When I stood up the pain remained constant. During the rest of the day, the pain was thankfully intermittent yet still lurking at or near the surface of conscious perception. I have during many years occasionally experienced joint pain (mostly upper arms and shoulders), never anything remotely as intense and debilitating as what I am now describing. I take no medications, don t drink or smoke, at age 70 lead a physically active life, am not overweight.