What's going on here? (Brooklynella)

Sorry for your loss dbo. This really sucks and I'm pretty sure I will be going through this tonight and tomorrow. I woke up this morning with a dead Atlantic blue tang. My wardley wrasse is fighting but does not look like it will make it. My bicolor angel has some white on it as does one of my clowns. My three green chromis and pink spot goby seem to be fine. Now I'm not sure if I have velvet or Brooke. Is there a easy way to tell the difference? I feel like this happened so quick that it might be Brooke but not sure. The tang that died has white all over, almost like what a humans skin looks like after getting sunburned and the skin starts to peel. The tang did also have a few dark brown spots on its sides as well.