What Causes Pain And Burning Sensation In Calf Muscles?

For the past two days I ve had a burning area in my left calf muscle kind of on the side of the leg about one inch below the crook of my leg and the area stretches about three inches to nearly the bone. It is raised but I cannot move it around. It hurts to walk. I have a hystory of varicose veins. Could this be another vein or blood clot? Is there anything I can do to treat it?