Sorry, I was sleeping and missed this. Just a logic check here: you dosed the medications AFTER the onset of symptoms, right? If so, then removing the medications would be a huge mistake. This is called "hunting and pecking" - people try a medication, and when it doesn't work right away, they try something else, or remove the medication. All anti-protozoan medications take 48 to 72 hours to begin to work. You need to stay the course. Coppersafe is the safest choice for protozoan diseases, but because it is mild, it takes longer to work.
That said, if this isn't a water quality issue, this looks like Amyloodinium, velvet. That disease kills so quickly that treatments after symptoms show are often not successful. That's why I advocate for preventative copper treatments from the start.
Mixing copper and metronidazole has been done, but I prefer to use one medication at a time if they are designed to treat the same issue (in this case, protozoans).
Also, you say your copper is at 2.0 with a Hanna? A full dose of coppersafe should be closer to 2.5
Jay