The causes of unexplained swelling and pain in the legs may be the following: First, long-term standing or postural discomfort caused by the patient’s work requires long-term standing, or the need to protect the legs from uncomfortable posture for a long time, this leg swelling and pain is likely due to long-term inappropriate movements, resulting in poor blood flow to the patient’s legs. The pain is usually more pronounced when the patient is working. After proper rest, the patient’s condition can be relieved to some extent. Second, vascular disease, if the patient is not often active, the blood vessels of the lower limbs may appear blocked, after a long time the patient’s blood flow is not smooth, the lower limbs may appear swollen. It is important to note that this condition is more serious and patients should be treated promptly to avoid causing a larger blockage. Third, internal diseases, if the patient has heart disease and other diseases, complications may also lead to the patient’s leg swelling and pain.