Fast acting spot remedies?

Okay so my PROM is on Thursday and i have the worst spot come up just above my lip... the worst thing is, it stands out REALLY bad when i smile and i just dont wanna look back on my prom pictures and be blinded by the enormity of this PLANET-LIKE spot!!! PLEASE tell me how to get rid of it before prom... or at least reduce the size to i can conceal it :/ PLEASE PLEASE PLEASE HELP!!! :S