How do I fix sun burn patches?

Yesterday I was at the beach and I was stupid and tried to put sunburn on my back by myself, this resulted in the little patches that I couldn't reach getting sunburnt. Now I have this little red areas and it looks so weird. The worst part is I have a banquet on friday night that I have an open back dress for. Is there anyway to fix those patches so it doesnt look so bad for Friday night????