I had this when I was like 13 and outside all day swimming during first real sun/hot day of the year while I was still all white skinned before (and I was looking like 10x more red than you in your picture). It was going through hell for like 3-5 days. Constant pain, no matter what I did, couldnt sleep, couldnt really eat, couldnt do basically anything since you cant lay down etc. More than one time during these days the pain was so huge that I had suicidal thoughts (like jump out of window just to stop the pain). No kidding this was the worst and most horrible days of my life.
But just like most pain, it heals and goes away.
I didnt know this by then but what really helps is putting yoghurt on your skin (or any thick milk products). This will cool down your system and fastens the healing of your cells.