Fluid rentention and the normal preg swelling. I was thinking maybe PE but GP always said it was just retention. Idealy raised above heart is best...but when at work its a bit hard.... so id try a box or a small stool even.... just so they are not flat on the groud. Move your feet around...like swivel your ankles to keep blood moving around as well.
Goodluck.. its not a nice feeling at all. I had it from about 28 weeks owards....and by 39 weeks i couldnt wear shoes, water from the shower hurt them when it hit.....and i thought it would go when bub was born.. but it hung around for another 2-3 weeks!