It all depends on what you want.
In all honesty food poisoning is a pretty hard case to make in a legal setting, particularly if you took it home and consumed it outside the restaurant. Did you eat it immediately while it was still at a safe temperature or did you let it sit around for a few hours first? Can you prove that? Can you prove that your illness came directly from the restaurant's food and not something else you ate or contracted in another manner? Did you save samples of the food, and/or your... shall we say, excretions? I'm not questioning the truth of your claims, just laying out the bare minimum of proof you'll need if you want legal justice.
If that's the case, and you feel you have a case, you'll probably want to contact an attorney first.
A possible exception to this is if many people were made sick from food at the same restaurant at the same time, contacting the health department may allow you to verify this, or at least alert them to a potential public health hazard. Assuming that you're the only one that calls them the health department's reaction will probably depend on who you talk to and what you tell them you want to do about it. Inspect the restaurant again? Maybe. Shut them down? Probably not.
If you would just like to alert the restaurant to the issue, which it sounds like from the tone of your question, call the manager or owner, or go in in person. Again it will help if you know what you want. Do you want an apology? An assurance that it will not happen again? A refund? Free food? Medical bills paid? A cash payoff to keep quiet? And again, the reaction will depend on who you talk to.
Good luck and a speedy recovery!

I got food poisoning from a well-liked bistro near the Hill and based on the fact that we had also witnessed unsafe food handling by chance (involving unwashed hands and cleaning supplies in an unsanitary area while doing prep) I chose to report it to King County. From reviewing their inspection reports on the County website I know that they actually got a visit.

They clearly needed some reminding.

Since then (and based on a few other instances of food poisoning) I've been wary of most soups or stews in restaurants because unless they are made fresh that day there is no telling how long they have been around and fomenting nasty bacteria.

This page has links to what you might be l

No matter what, 1st call the restaurant so they can pull the offending product immediately!!!  I know as an owner I would want to know so I could avoid further spread of both illness and potential harm to my business. You are being helpful, not harmful but informing them!

Sure, report it to the Health Department if it makes you fell better but it's not going to prevent more people from getting sick. By the time they follow up the chances are 10 more people will contract the same illness. This is especially an issue with Shellfish!

Most food born illness will work it's way out of your system pretty fast. We have all consumed spoiled milk. Within 15 minutes abdominal cramping ensues and after 2 hours the episode is over....Shellfish is a more serious illness.

This is a particularly good site to self diagnose: http://www.foodpoisoning.com/symptoms.php