not only....Not only is it not ok for you to go in for the ethical reasons, in most states it would be illegal for you to go in. Let me put it to you this way:
If you felt bad and went to work, but had no idea what was wrong with you, it would not be ok, but it would not be ethically wrong, or illegal. You could reason, "well, I figured I was just feeling a little run down from all the hours I have been working." Or something to that effect.
But, you have been to a doctor and have been told that you have one of three possible things, ALL of which are cause to keep you out of the kitchen from an ethical perspective and a legal perspective. If you take a couple of customers down and the Health Inspector comes in they are going to check your - and everyone else's - medical records, and they are going to find out that you knowingly put people at risk.
This is how this plays out....
You lose your job, because the owners are going to fire you right away as a Public Relations reaction. The restaurant is going to be sued, and the owners are going to sue you in turn. Also, the customer who got sick is going to sue you.
Now, I know you are concerned about missing four days when you don't know which ailment you have, but... you DO know you have at least ONE of those ailments. Fact is, all of them are going to knock you out of work for a minimum of a week. Mono will take you down for a month! In the end though, being out for four days is better than being sued twice and losing your job. Chances are slim that the worst case scenario I just described will happen, but why risk it?
Worried about the money? Take the time off, and go to the labor department and apply for medical leave unemployment insurance. Your employer has been paying into it, and you have been paying taxes. Now is the time you use it.
I once tore all the ligaments on the left side of my left ankle at 3:00 in the morning, working, got out of the hospital at 6:00 AM and was back on the line cooking at 9:00 am. I get it man. I know you have to be tough... but you do not have to be dangerous.
Get well soon.