I think you increased copper WAY too fast. Most people will increase copper to therapeutic levels of 1.5-1.75 over the course of several days to a week.
This fish didn't have a week and I only dosed 2 ml and was planning on doing another dose tonight and then tomorrow morning. I have done this before with a Purple and Powder Blue Tang that had Marine Velvet and they made it through fine. The Bristletooth in the tank is fine as well.
Not to discount your post, but I don't think it's a reaction to the copper.