My Ankles Have Just Started Swelling In The Past Week.

My ankles have just started swelling in the past week. I am not aware that I sprained my ankle. But for the last week everyday it swells up during the day and it is painful. During the night the swelling will go down, but once I start walking around the next day it starts all over again. I am 61 years of age, height is 5' 4", 180 pounds.