Swelling of both legs and feet may be induced by heart failure, kidney disease, low albumin etc. Besides leg swelling, do you have swelling in other body parts such as eyelid etc.? How about your heart, kidney and liver function? On the other hand, you can have an ultrasound scan to see whether you have blood clots in both legs. When you sleep at night, put your leg at a relatively higher level than your body to relieve the swelling.