You might just be getting yourself worked up. You might have a little cough, or tickle, and your mind is playing it up and dramatizing it because of your nerves. If you really think you're getting sick, try gargling with some warm salt water, and maybe taking an over the counter thing like NyQuil or something like that. Get lots of sleep, and drink lots of water. Cough drops might help too. But you have to get the ones that actually do something. Not the wimpy ones that just taste good!
I think you'll be fine, and congrats! Have a wonderful life and a very special day!