New, persistent leg pain certainly warrants a visit to your doctor for evaluation. Leg pain can have many causes, but your description of aching after prolonged standing or sitting suggests a possible buildup of fluid in the leg veins (venous congestion).
Venous congestion occurs when the valves in your leg veins don't work properly to keep blood moving efficiently from your legs to your heart — a condition called venous insufficiency. Instead, blood pools in your legs and feet, causing pain and, frequently, swelling. People with venous congestion typically describe the pain as a burning or cramping sensation, mainly in the calf.
Past inflammation of a vein (phlebitis) may damage the valves and lead to venous congestion. Poor function of the valves in the leg veins also contributes to varicose veins — distended veins visible just beneath the skin. Varicose veins also may lead to venous congestion.
Wearing knee-high support hose may be worth a try to ease discomfort associated with fluid buildup in the legs. Ask your doctor for a recommendation.