Okay, there are several things that work.
1. Take a chilled cucumber (maybe more than one). Cut fairly thick pieces out and lay them on the burnt area. Yes --it will be cold-- but it works.
2. Take plain white yogurt and put it on the burnt area, allow it to soak in and then take a cool bath --not cold--.
3. Call your doctor and ask if there is a certain lotion/cream he would suggest for a bad sunburn like that.
4. Be miserable and don't do anything about it. But that's not the greatest idea.
Also, next time you go out to do something like that, take precautions and saturate yourself with sun lotion so you don't burn. Severe sunburns on the same areas over and over can result in skin cancer. Trust me, I'm 14, my grandmother had skin cancer, my nose is always getting sunburned and my dermatologist told me what the consequences are.
There's my two cents. Spend it wisely.