Goldfish has whitespot

Question
Hi Will,

I bought a goldfish and a 30 litre tank for my daughters birthday.
I filled the tank with tap water and emptied the solution I got with the tank to de-chlorinate the water. I waited 7 days before buying a goldfish and putting it in the tank as the store owner instructed.

About three days later, the goldfish started to get small white spots on it ( about the size of a grain of salt ) I was told this was white spot or Ich.

I went to the store and bought the appropriate  treatment and added the appropriate dose. Four days later I added another dose as instructed by the fish medication leaflet.

My goldfish is now hanging vertically in the water, it has red blotches on or just under it's scales ( i can't really tell by looking through the tank )and it's gills are moving very fast.

Also part of the end of it's tail has come off. Where there used to be four trails there is now only three which look quite ragged.

I've done the correct water changes and also removed the carbon filter from the main filter as I was told this would impede the medication.

Any help would be great as my 3 year old autistic son is quite attached to it and I really don't want it to die.

Thank you so much for your time

D

Answer
Hi,
Sounds like ammonia poisoning. The person at the pet store should have said 1 month not 1 week so the cycle can complete it's self. All you can do is a 20%-25% water change daily and hope that helps. sorry to say this, but it may be too late.
Best Wishes.