In addition to what people have advised so far, I can’t stress enough how important rest, and especially sleep is when you’re ill. Whenever I’ve fallen ill with a cold, flu, cough, etc., I find that if I try to fight it and go about the day as normal, the illness lasts much longer. If I try to sleep it off, I get better a lot faster. If you can, and especially on the first day, don’t go to work, don’t run errands, and especially don’t go to the gym/exercise. Good luck!