why dose your feet swell up?

There can be many reasons why your feet swell up. Are you diabetic? Do you have heart problems? Sometimes sitting for a long time can decrease the circulation to your legs and feet and cause swelling called DEPENDANT EDEMA. IT could be an allergy to food, congestive heart heart failure, kidney problems. MANY reasons. But if this is new and you haven't seen a doctor for a long time, go see your doctor. IF this is something that just suddenly happened a few minutes ago.... you might need to go to urgent care to find out why. At any rate, we should not have swelling on our feet. There are many diseases and conditions that can cause this. WIthout knowing your age or activity or medical history this is a tough one to answer. But it is NOT normal for your feet to swell up very large as you discribe and seek medical attention soon. IF this suddenly happened just now, GO NOW TO ER or urgent care as it may be an allergic reaction to something!