Hypothryoidism can contribute to peripheral edema. Do you have hypo or hypertension? You may also want to try soaking in epsom salts. It creates a hypertonic solution that draws the water out of your body. Additionally, try to get up and walk around at least every hour at work. While you are sitting down, prop your feet up.
There are many things that can cause peripheral edema and only your doctor will be able to figure it out after some tests.