What Causes Pain And Swelling In Left Calf?

Hello: about a week ago I began to feel a pain vertically along and below the left calf,I thought it was a strained muscle or tendon. Over time the pain seemed to settle around the back of the left ankle.
After a few days I noticed the left ankle was larger than the right, it dose'nt hurt while walking but
When I touch it it's painful,will this pain and swelling go away on it's own?