Welcome to the forum! Sorry to hear about your troubles...I think you came to the right place though.
I think more information would be needed to help you out faster and with less guess work involved.
What size tank are you using?
How long has the tank been up and running? (Is this a new tank with a new fish that you got for Christmas or did you have the tank before?)
Have you ever tested the tank's water for ammonia, nitrites, or nitrates?
If so, what did those tests say?
If not, are you familiar with the principles of 'cycling' a tank?
Just because this is a common problem for anyone new to the hobby (including most, if not all of us when we started out), I would guess and say that your fish is probrably suffering from ammonia poisoning right now. If you want to learn more about how this happens, why it happens, and how to avoid this in the future, read this sticky article on cycling a tank:
http://www.fishtankforums.com/5-fres...-aquarium.html
For now, I would do a water change and take out about 50% of the water and replace it with new water. Make sure that you are also using a chemical that will remove the chlorine from the tap water...if you have some. If not, get some asap since chlorine can be very bad for your fish and it is usually found in most water sources, especially city water.