Why Do My Feet Swell?

The guest gave a very good answer, would only add one more thing.
   It is difficult to know for sure why your feet are swelling without seeing a doctor.
Swelling of the feet and/or legs can sometimes be due to heart problems.
If the problem persists, would be good to make a dr. Appointment.
  It is most likely water retention/Edema, but best to be safe.
  Good luck to you.

Edema, water retention. Go for long walks and drink 8 glasses of spring water daily. Garlic is good too. Allicin, the active ingredient in garlic is destroyed within one hour of smashing the garlic. This means that garlic pills are virtually worthless and should not be used.
Instead, when you use the garlic, compress it with a spoon prior to swallowing it, or put it through your juicer to add to vegetable juice. Just be careful not to put too much as raw garlic has a powerful flavor and can cause some unpleasant surprises. A single medium size clove or two is usually sufficient.
Do the above for a week and see if you are better. Certain medications can cause this too, or high blood pressure.

Are you on your feet alot? Or do a lot of sitting, try putting your feet up instead of letting them hang all the time.