This pain occurs when your veins start to have a problem sending blood back to your heart from your limbs. The blood then begins to pool in the legs. Some of the causes for this condition are varicose veins and deep vein thrombosis, also known as blood clots. There can then be swelling, ulcers of the leg, and pain. Treatment depends on the cause of the condition but may include surgery and/or prescription medication.
Vascular-insufficiency pain Joseph Smith, PhD