After Surgery On My Right Leg 2-1/2 Years Ago, I

After surgery on my right leg 2-1/2 years ago, I developed a blood clot. Was put on medication and did not have any other problems. I was told that once you have a blood clot, you are more prone to getting them again. Is this true? A few months ago, I developed a tenderness on my lower left leg. It is red constantly and sometimes warm to the touch, sometimes tender, sometimes not. Could this possible be a blood clot?