Congrats on the progress to date, you are ahead of the game and will be prepared for new additions later
First off, it is just the fish in the hospital tank, right?
Copper would be best if it is Amyloo. Don't go there yet. I would suspect the clowns in the pet shop would show signs of it now. Have you been shopping for supplies in the same shop the clowns were sourced from? If so, are the remaining clowns covered in junk, swimming head up or down in the corners?
I also suspect frozen brine should be on the buy list for today or tomorrow. Try to get get an enriched type, I pick up spirulina enriched personally. This should be easily obtainable and even though folks will come out of the woodwork decrying it's non-nutritional benefits, my breeder clowns don't seem to mind it mixed in with a good variety ;>)
Locating a local shop with PE mysis and cyclopeze will be a bit more difficult but the local fish clubs should be helpful.
Getting them eating, and eating well, is the next real task.
Be on the look out for them swimming in place head up or head down.
Be on the look out for a whitish slime.
Continued good luck and patience.