What he was doing is called "flashing".
He was flashing a rock which could indicate that he was trying to use it to scratch an itch.
An itch, or flashing can be for almost any kind of skin irritation or parasite, so flashing in itself doesn't necessarily mean Ich... but since you are also seeing white spots... it's almost a certainty that's what it is.
Here's a brief article by Fluff on Ich: http://www.aquariumadvice.com/articl...q=2&fldAuto=50
There's also a wide variety of treatments and methods for dealing with Ich.
sterilizers, herbal treatments, vitamin supplements, going fallow, hyposalinty, freshwater dips, etc., etc.
You can do a search for Ich in the saltwater forums using the link at top and read up on a lot of other people's experiences to help you along.