I did find a forum talking about sunburn - "Extreme Sunburn....i Cant Walk". Here is one comment you will be interested in reading..
"Sunburn24 Hi guys, ive had the same problem with a sunburn i got a month and a half ago i went to three different dermatologists, and the problem is that the heat caused the tiny blood vessels under the skin to rupture. This is why my legs are purpulish red and hurt when i stand up. The blood rushes down the body to the legs when standing up causing the pain. Since the vessels are ruptured the blood ca not be well contained therefore causing redness pressure and pain. All three doctors advised me to stay out of the sun, keep myself cool, as heat aggrevates the problem, and keep legs elevated above head level as long as possible. The healing time however depends on the person's body.. Might take from three months to a year sonetimes and there are no medications for it.. The more one rests the faster the healing process.. May god help us and Goodluck for us all! PS: my wedding is in two months! So i really hope im better by then!"