What Causes Swelling And Pain In The Ankle?

My ankle has been swollen for about 5 weeks now and goes from no pain to excruciating pain. The swelling is on the outside of the left foot and has been constant throughout the entire time. Sometimes the inside of my ankle will swell and the pain will increase. I am also experiencing numbness in my toes and foot recently. I have not sprained it or injured it at all. i have also noticed pain at the top of the back of my ankle and actually could not stand up for more than 5 minutes.