If I were you I would just go to the dermatologist and get it injected with a cortisone shot. I guess it completely heals big cysts overnight.
But, then again who has time to make the apt., etc.?
I wold just put a thick layer of benzol perox. on it and keep replying it. The b.p. kills acne bacteria and helps to reduce swelling. Just use a 2.5% or 5% formula...it's just as effective as 10%, but without all the extra irritation.
Also, you might want to take some ibuprophen. It will help with inflamation.
I hope this is some help. Try not to worry too much...focus on your meeting. You'll do fine!