Stings and Bites: Again, if it's only on one side, a bug bite or Meridian Health Protocol Review sting could be the cause. If the swelling is severe, it's a good idea to see the doctor. You may need something stronger to counteract an allergic reaction. Rest and elevation are a good idea, and the doctor may suggest an antihistamine as well as an anti-inflammatory medication.
Arthritis: Osteoarthritis, rheumatoid arthritis and gout can create swelling in the affected joints. It can attack both feet and ankles or it can be located in just one. Usually gout starts in the right foot. Your doctor can give you exercises to do that may help improve joint function. You will probably be put on anti-inflammatories as well.
Heart Disease: When the heart has difficulty pumping blood, it can build up in the lower legs and feet. The treatment for this is a little different than that for the above conditions. Blood flow has to be improved, and excess fluid removed. The doctor may suggest diuretics, which should improve the swelling in your lower limbs. There are many medications that might be prescribed, depending on the exact cause. You will probably be put on a low sodium diet to prevent fluid retention.