I am, by no means, trying to defend the actions of the restaurant staff, but being a former restaurant employee myself, I don't think people realize how...short-sighted some of these employees can be. I can give you many examples of similar things happening, only b/c the employee does not STOP and THINK about what the customer is saying. Or perhaps it's b/c they're not well-trained, but it's probably a little bit of both.
When a customer comes in that has an allergy, it's the restaurant's responsibility to accomodate them as best as they can. Sure, that might mean a limited menu, or customizing their order, but they should do that since it's probably hard for this customer to be able to dine out to begin with, and they have chosen this establishment to dine at when they could have chosen another one instead.
This is why I am always wary of dining out (although, I do dine out quite a bit). For example, I would frequently see the salad boy or another kitchen employee, when asked to take the garbage to the dumpster, reach in, push the garbage down to close the bag, carry it out to the dumpster, come in, and then resume to make salads/cook/whatever. Hello! After you've touched the garbage, you need to WASH YOUR HANDS! It's stuff like that that makes me curious as to what exactly am I eating when I receive my order.
Anyways, I've gotten off topic. Please post to let us know that you're feeling better, and what happens w/ the restaurant (sue 'em!).