Clownfish,
The clams must have been already dead - clams cause a lot of problems in tanks and you have to be very careful with them. Frozen shrimp that you thaw out when you need it is a much better choice.
Take out the clams and change the water using in the two gallons of salt water that you have - I've assumed that you've already made up the salt water. (You should always have salt water on hand for emergencies.) Tell your parents that you have an emergency and drive somewhere that has distilled water - most grocery stores do, usually in one gallon containers. Get distilled water to make up a lot more salt water. I don't remember the size of your tank, but if you have a 30 gallon, I'd get 10 gallons of distilled. Make up this water, mix with a pump. You shouldn't put it in immediately - it has to mix for at least a few hours.
In the meantime, change whatever carbon you have in your filtration and I assume you're using your protein skimmer.
Any other suggestions from other Tonmo members?
Nancy