I don't think there's anything you can do but wait for the swelling to go down. It might be painful for a couple days but don't mess with it. Try and put rubbing alcohol on it to try and dry it out.
I have a large pimple near the bottom of the buttock and it is the size of a quarter. It is very red and swollen and has sort of a brownish color head and is very very sore. This is the third day and was wondering how long it takes for the soreness to leave.
Put Alcohol on it , dabbing gently, several times a day, as often as you can. This will bring it to a head quickly.
You could try warm compresses. The warmth somehow brings it out. JUST DON'T POP IT. It just isn't good for your skin.
I bought the zeno zit zapper and it works really good! They're not too expensive at walgreens.
Put a masque on it, let it dry, clean it off. Then go to sleep with honey on it. (you might want to put a bandaid over the honey)