Hello! I Was In The Sun For Over 4 Hours

Hello! I was in the sun for over 4 hours exactly 7 days ago. I have a sunburn on my right and left shins....but the skin is red, blotchy and almost purple in color. It looks more like a bruise than a sun burn. On the right shin, my skin is white and flakey.
Why does my skin looked bruised and will it eventually go away? What can I do to help my skin? Do I need to go to a dermatologist? Many thanks!