What Causes Pain And Swelling In Ankles And Legs?

I went to run and something popped in the calf of my leg and I had severe pain. Was not able to walk on foot with out limping and walking on toes. Cannot put weight on foot. I put ice on it when it first happed and have been wearing an ace bandage but did not wrap it today. This happenedd on Saturday, 3 days ago, still have swelling of ankles and leg. There is a red circle right on the calf of my leg about the size of a tennis ball and the whole leg below knee is sore and swollen. Have not went to the doctor to have it x-rayed. I know it takes awhile for this to heal. Should I be worried about blood clots?