If it is venous it will hurt when you bear weight and touch or bend your knee. The worse pain should occur when you are bearing weight on it. At rest laying down and not moving the pain will be minimal or nonexistent. It is usually swollen. It might feel like a knot is there or a lump and it might be red. If it is in the artery and blocking blood flow your leg will be very painful no matter what position and foot/leg will be purple/blue/black in color and feel very cold to touch. The artery blood clot is very serious. You need to go to the ER to have it check out right away. For the venous one you still should go to the ER because it is to late in the day to see you doctor and it will take longer to get an ultra sound set up. Good luck.
