There. There are several possible explanations. They can be narrowed down by considering the nature of the pain and when it occurs. Pain that is present all the time, or that begins immediately after you stand up, suggests a musculoskeletal problem or arthritis. This is especially true if the pain is at the joints. Pain that is crampy in nature, begins after you start walking and goes away when you stop and rest, or starts when you are lying down but gets better when you hang your legs off the bed suggests arterial blockage. Itching, aching, or a sense of fullness in the legs that develops slowly over time when you're standing up and is relieved when you lie down or when you exercise suggests a problem with your venous system. In addition to the history questions discussed above, there are some signs of each type of problem that your doctor can look for on a physical exam. In some cases, x-rays or ultrasound studies might also be needed.