I've only been to 5 furry cons, and about 10 other gaming conventions. I've never gotten concrud at any of them. I was sick with a slight illness in the weeks before leading up to AC2007 and I was taking antibiotics for that.
I know you didn't say "rest", Jade. But it is the best thing you can probably do right now. What other symptoms are you having? If it's the flu, you need to stay hydrated. Drink water only. No sodas, coffee, alcohol. If you drink OJ for the vitamin C content, you only need to drink one 8-12 oz. glass a day. No more than that. Depending on what your condition and other symptoms are, I'd recommend staying away from greasy, fatty, fried foods. Eat more healthy stuff like fruits and vegetables, soups.