What would cause several varicose veins to suddenly appear on legs? also have sudden onset of patches of spider veins around ankles

IT is: called venous insufficiency, too much pressure in your veins blood is going back down your legs instead of returning to your heart. Wear compression stockings, elevate legs as much as possible, see a doctor, some surgery can be done to the veins.

Unhealthy valves: Varicose veins can appear at any time in life.They are caused by unhealthy valves in the veinsThrse valves can leak and blood falls back due to incompetency and gravity makes blood gathered in the veins and they get to be seen bulging and engorged.Spider veins are varicosity in smaller superficial veins.These can run in families,so there is genetic predisposition here.

Possibly: Varicose veins and, frequently, spider veins are due to underlying leaking(refluxing) valves usually in the saphenous system. Stasis of blood in the veins occurs when the calf muscle pump is not being used such as with standing or sitting in place for long periods of time. Sudden onset of new veins suggests venous valvular insufficiency. See a vein specialist for a full vein eval.