This definitely looks like Brooklynella...and the damsel family of fish are highly susceptible. Treatment must occur quickly since this can kill the fish quickly. By the pictures, this is starting to be very advanced.
Treatment is either a 45min Formulin bath or 90 min Ruby Reef Rally bath -- then put into a new quarantine tank while you remove all your current fish and place them into the quarantine system as well. Then, treat the quarantine tank (since it has fish who have been exposed but possibly not showing signs yet) the water column with Metrodanizole every 48hrs for 14 days. This should help to eradicate it from the other fish as well.
You can also do a 5 min Freshwater dip to help relieve this particular fish somewhat while you wait to get the meds, if you don't already have present.
Sadly, your current tank will have to go fallow from all fish for 76 days!
Sorry that this sounds like your first fish experience in your new tank. But, it shows the risks and dangers of not quarantining your fish prior to insertion into your main tank!