I have a purple tang that’s in QT with coppersafe 2ppm and prazipro. He’s been in QT 3 weeks. I had an ick outbreak after removing rocks and shifting sand around.(I sold some old decor because of upgrading to a larger reef ready tank). Notice my clown and another got ick, so I went ahead and QT all fish while waiting for new DT tank to cycle. A few days ago I noticed purple tang has developed some sort of skin issue near head. Any ideas what this could be? I’ve removed him from coppersafe and prazipro and QT in another separate tank. I was planning on using general cure or apr E.M. Erythromycin to treat. Any help would be appreciated. He’s eating normally.