What Causes Strained Muscles In Inner Thigh Radiating To The Tail Bone?

I have what I think is a running injury starting with a feeling of a strained muscle in my inner thigh/groin area, which now radiates up into the tail bone and vaginal area, making it difficult even to sit. Does this sound like a running injury and should I completely stop running, see a physiotherapist, or just take it easy?