It could be an allergic reaction to medication. I know a woman who had a reaction to antibiotics - her legs are swollen and actually weeping from the skin stretching so much. She is taking antihistamines and her mother is helping by bandaging and wrapping her legs.... Also, heart trouble can cause edema.
Swelling in both feet and ankles is a hallmark of fluid retention. If it continues for two weeks you should see a physician for an evaluation. Try 2000 mg of vitamin C a day in two divided doses. This is a mild diuretic. Do not self-prescribe diuretics other than vitamin C.
probably not the direct symptoms of an infection but maybe still a Immunological problem.
you could get a appointment with a Rheumatologist