Are they like sores, or is the color under the skin?
Firefish are almost translucent, so on mine you can see their gills a little bit through their white parts. It doesn't look anything like that though, might want to google Uronema marinum and see if the pics match. If you don't get good image results try "chromis Uronema" they get it a lot and it's easy to see against their blue flesh.