My feet are swollen what could be the cause?

Too general: Swollen feet could be anything from heart failure to venous insufficiency . Gout and other causes shout be evaluated too. Need more clinical information. Go for a complete history and physical blood work and possibly a doppler will give us more information.

Many causes: Swelling = retaining salt/sodium + water. Could be kidneys retaining, could be medicines (such as Nifedipine or amlodipine or nsaids). Could be heart or kidney failure or obstruction of venous drainage (veins valves are incompetent or mass in abdomen). Other causes. If persists, best to seek help, especially if any trouble breathing.