Oh, I understand your frustration, it's not a problem. Online fish illness diagnosis is not an easy thing, all too often you have to take a wide ranging "shotgun" sort of approach. Your larger hatcheries have facilities for identifying the particular cause (microscopes, dissection, personnel well versed in their use) and can narrow it down & formulate a specific treatment plan much easier than anyone can online.
I've found with trying to figure any sort of online treatment it's best to start with the least invasive or harsh method or medication, and work from there. The quinine sulfate is for medication resistant ich, which is out there, but I would not assume it is that right off the bat. The copper will treat ich as well as velvet, or most any other sort of external parasite. It has external antibacterial properties as well. Metro also has an antibiotic effect, and is often used for this in dogs.
I've found with trying to figure any sort of online treatment it's best to start with the least invasive or harsh method or medication, and work from there. The quinine sulfate is for medication resistant ich, which is out there, but I would not assume it is that right off the bat. The copper will treat ich as well as velvet, or most any other sort of external parasite. It has external antibacterial properties as well. Metro also has an antibiotic effect, and is often used for this in dogs.