I have a date tomorrow.. & my cold sore got BIGGER !?

I have a cold sore & it wasnt that bad yesterday..bit i was still putting stuff on it. Now today its even BIGGER and very noticable. Putting lipstick or gloss...something with color would not take away the fact that one side of my upper lid is way bigger than the other side....what do i do ? I have a date tomorrow....& i cant cancel.