one time, in my third trimester, I walked 14 miles barefoot on the beach and got a bad sunburn on my feet too. they swelled up so bad I couldn't walk. I tried diluted vinegar, Epson salt, Tylenol, so many tricks... the best thing I did was, I drank a gallon of water in one day and got a great foot rub. I did this for 3 days and it finally went down after I had been so swollen for 3 weeks.... I feel lucky though, my dad's feet have gotten so swollen in the past from infection and blood clot, that he got stretch marks!