You could see how much salt is in your diet. Several cheeses have a high salt content,
http://www.theguardian.com/lifeandstyle/wordofmouth/2012/nov/29/how-choose-healthier-cheese
Lots of processed meats, ham, sausages etc.... vary in their salt content. They usually label it as sodium.
Salt is not a problem for most people unless they have a high BP but it could be the cause of your swollen ankles.
This article might help, you can get OTC diuretics but do tell the chemist which medications you are taking.
http://www.wikihow.com/Reduce-Water-Retention
Massage also helps. This article explains how to massage your ankles.
http://www.sofeminine.co.uk/mag/health/d5754/c128066.html
I drink at least 3 litres of water a day and do not drink diet sodas preferring to add lemon and lime slices to water.
If you do not get an improvement then you must go back to your Dr. and explain that the swollen ankles are causing you distress.
Hope this helps,
CC.