Swollen foot... getting scared

I am on my feet a lot.... and it’s to the point where My feet hurt soooooo bad. Like unbearably bad. I noticed they have been swollen (especially the left) these last couple of days and it’s starting to concern me. :( like I’m getting scared. I go to the doctor on Wednesday so I am going to see but has anyone experienced this or could this be a sign of preeclampsia? It’s weird because it’s mainly only the left one that’s swollen. The picture doesn’t show it as much but its bad.