What to do about swelling & numbness in legs/feet?

Millions of causes. Your complain is very general. Things that cause those include allergic reactions, heart failure, severe malnutrition, fluid overload, vein disease, etc. Swelling and numbness are very non-specific finding and have so many causes that identifying them takes more than 400 words allows me to help. If it is causing you problems, then getting a doctors opinion should give you peace of mind.