How To Cure Blotchiness And Swelling Around The Ankles?

I am a 33 year old woman who occasionally suffers from a bit of blotchiness or perhaps a swelling right around the ankles (alternately). When that happens, the affected side (region) gets very itchy (the kind of itchness that makes me feel like I should open it up and scratch on the inside). What could be the possible cause of this?