What Causes Pulsations In Calf Muscle And Bulge In Knee?

When I'm laying prone or sometimes when I'm sitting down I feel my pulse in my calf muscle where it bulges out a bit, about halfway between the bend in my knee and my foot. I have had a high caffeine intake to day (6 cups of coffee in about 5 hours preparing for exams). I am worried about deep vein thrombosis.