What Causes Pain And Tenderness Below The Knee?

I woke in the middle of the night to go to the bathroom....and when I stood, I noticed discomfort in my right leg, on the inside of my leg, below my knee. Tenderness and perhaps a new varicose vein bump. Feels tender like a bruise, but more painful than just tenderness. Only hurts to the touch, not when sitting or standing. I actually ran a few miles this morning before going to work. No pain then. Area feels a bit stiff, like a bee sting. Have iced the area most of the afternoon and now with my leg propped up at home. Should I be concerned about a blood clot? Does it go away?