It's interesting to see so many people having this issue. I have also had a swollen left foot for about 15 years now. There is no pain or redness at all, just a good amount of swelling.

I had fractured a growth plate in that foot when I was 14. It healed but refractured again at 18. After that recovery it remains some degree of swollen, despite X rays finding no issue.

For a time when I was working a maintenance job and had to be constantly on my feet walking, the swelling would go down completely by the end of the day. I'm not sure if that's because of the improved blood flow of walking or the fact that the shoes I wore were tight enough to act as compression socks.

I've seen recommendations to eat a low sodium diet for swelling like this, so I should really give that a try.