Hello, The visible paining vein that you are seeing at the back of the leg and the intensity of pain which increases when you stand or walk for longer time indicate towards the possibility of varicose vein. Veins are the blood tubes that carry deoxygenated blood from various parts of our body to heart and lungs. If these veins become abnormally thick, twisted or tortuous, they are called varicose veins. Usually these happen in elderly people, but if there is some abnormality in the vein wall, you are obese, your routine requires you to stand for very long periods of time then younger people like you may suffer from it, too. To get relief from this, you need to wear compression stockings that are available in medical stores. Do lots of exercise. Elevate your legs while sleeping and if possible, when you are sitting. Try to avoid continuous standing periods. If you do not find relief in symptoms or then worsen, you should see a physician for physical examination. I hope this information helps. Thank you for choosing HealthcareMagic. Best, Dr. Viraj Shah