Also this entire discussion is irrelevant about ich if the op has velvet. "Velvet management" methods don't really work. In today's environment velvet is every bit as common as ich and if you try ich management as suggested by some in this thread, you will get velvet and you will lose this battle. You'll also not be able to keep most acanthurus tangs (like powder blue, powder brown, goldrim, achilles, etc) and many angels and butterflies as well. You limit the fish you can keep. If you push your luck with these fish there's a chance you start an infestation that takes over quickly with an easier, weaker host.
I still think based on what little the op has provided that this is a case of velvet. The treatment would be the same, but the need to act quickly is imperative.