That sounds awful, dragon... bet you are draggin' (haha... sorry).Sounds like you are allergic to something.
First of all, the reason you are in pain is the pressure from so much yuck in your sinuses. We had a long discussion about that on the board here a couple of months ago. Basically, you need to clear tht out and the best way is by clearing your sinuses with some saltwater snorted up your nostrils, one at a time.
I imagine you are pretty stuffed up, so it won't be easy and you'll need to do it more than once. Start asap... do it again about an hour before the presentation and maybe one other time inbetween.
Make up a warm salt water mix -- should taste about as salty as the ocean --hold about a tablespoon in the palm of your hand, pinch one nostril closed and sniff that up the other. Do this over a sink as you're likely to make a mess. Do this a couple of times in each nostril. If you can, afterwards, put hot as youcan stand water on a wash cloth and lay it over your face. Repeat. That feels great, doesn't it?
Ultracet has acetominophin which I avoid. I'm an advocate for Advil + Aspirin, but whatever you do, continue to use some sort of analgesic -- just don't overdo it. I'd dump the sudafed sinus stuff. Find some plain sudafed... little red pills. It is better to use single symptom meds, rather than doubling them up, 'cause then you can control them better and won't accidentally overdose on tylenol.
The salt-water rinsing should work and you can do it at work. Just go to any deli or fast-food place and grab a few packets of salt (and some napkins). Then head to the restroom. It is a little gross... a little uncomfortable, but will give you, in the end, a lot of relief.
To counteract your allergiic reaction (I assume the sinus attack is from allergies)... what are you taking? Claritin? A prescription? Anything? I've found that a tablespoon or two of good honey always makes me feel better... but I like honey.
I hope you feel better quick and let us know how you're doing.