It sounds rather like the issues I have with water retention/oedema, the first of which I've had intermittently for many years and from well before I was ever diabetic. For me I belieive water retention has in part been a combination of blood pressure, being on my feet for long periods and hot weather, but the oedema has only been a problem since last year and is far worse than just my fat ankles.
As a temporary measure try to keep your feet up whenever possible - as my GP once charmingly put it "keep you feet higher than your bum"... it will help reduce the swelling for the time being. But definitely get things checked out as already suggested.
Robbity