For the past few days I have noticed that my right saphenous vein is very rigid after being standing up. Besides I have a knot that apparently is movi?

Could be. A superficial plebitis - inflammation of the vein.
Is it painful? Is the "knot" painful? We inherit vein disease. It can present as large surface veins or with faulty valves in the inside that cause blood to reflux or go backward down the leg, which is the wrong way and cause pooling, distention, knots, and symptoms like aching, cramping, restless legs, phlebitis (a tender hard knot), etc. You should have a consult with a phlebologist: www. Phlebolgy. Org.