Can you get a clearer picture? I think I can make out some spots that could be crypto, but brook can have that kind of look too and the treatments are different. Turn your lights to the white spectrum and try to get a clear shot of him. Is there a white mucous as well as the spots?
I've read that copper may just suppress the symptoms and is unlikely to completely get rid of it so I would have to recommend the usual treatment: 45min bath in formalin(Quick Cure) then move to a QT and treat with chloroquine phosphate or metronidazole for a 14 day period. FW dips can also help. And the DT needs to be fishless for 6 weeks.
/But if this was brook and went untreated, that fish is likely a goner by now.
There is a little trick you can try that I found works well. Get one of those clear plastic hamster balls similar to this:https://www.amazon.com/Kaytee-Run-about-Mini-Exercise-Clear/dp/B0002AS8QQ. Put the clown in that. The other clown(s) will see it over the next few days and then once its released you have a good chance of them all getting along. I did this with a gold flake clown. The existing Lightning clown is about 3" inch and has killed all previous attempts to introduce new clowns to her. The gold flake and lightning are both hosting 8 'nems and laying eggs every few weeks.