I am one of those people that feel that your health is one of the most important things you own. If you’re not feeling up to par, you won’t be able to get around to accomplishing even half the things on your long list of things to do. If you are feeling ill, you are a risk to your co-workers and even more so, in danger of becoming even more ill if you don’t take care of yourself. Not to mention, at the end of the day, you won’t be able to be a productive employee — if this is what you’re really thinking is the reason you must go to work.
If by not going to work, your employer will not pay you (that is, he will not grant you a paid sick day), then either try to bring about change in your workplace or leave your job. If you live in a country where every one tells you that it doesn’t matter if you change your job, the same situation exists everywhere, then find another way. Your health and your well-being are IMPORTANT.
So go home, drink some tea, and get some rest. You’ll need it.