What's the best way to get rid of major sunburn and swollen feet?

Ice and aloe. Ice will reduce swollen feet and aloe will sooth sunburned skin. Ice for 20 mins and re ice in 40 mins.
Aloe for the burn. Along with antiinflammatories. Elevate the feet for the swelling.
See your Dr. . Sunburn can be serious. You may need both topical and systemic medications.