You have not mentioned your age. Swelling might be due to increased BP which needs to be evaluated. Your age and your weight are the contributing factors for BP(which you have not mentioned). Try to get a Random Blood Sugar level also.
There are many causes for swelling of feet but it is mainly due to fluid retention due to pathological events in the body( except pregnancy
) . these pathological events can be found out when you present yourself for proper examination to a physician.
Pls drink water and don't restrict the intake of water. regarding the low salt intake you need to consult a doctor ASAP.