The causes of foot swelling and pain are as follows: First, vascular diseases of the lower limbs: for example, varicose veins of the lower limbs, which tend to have venous valve insufficiency, cause obstructed blood return and poor return when straining and walking more, so blood will accumulate in the feet and cause swelling of the feet. Second, venous thrombosis: The main cause is similar, which is caused by the blood being blocked by the thrombus and unable to flow back. Third, herniated disc: When a herniated disc compresses the nerve root, there will be radiating pain in the lower limbs, including pain in the legs, pain in the feet and numbness.