Suggest Treatment For Pain In Left Butt, Thigh And Calf

I am having pain in the butt, thigh, and calf on my left side. I had a MRI and will have a bone scan Monday. Is this just inflamation that will go away? The Doctor said it could be an infection. I have had 3 surgeries to open the space for the nerve to pass -- I had the same pain then too. This Doctor said L5 shows inflamation -- please explain what I have. He said it could be an infection.