Sorry, I wasn't aware the "spots" you were talking about was the Ich. Some very experienced people here have not seen any beneficial results from using Melafix. Many others claim they have.
As far as everything I have heard, Melafix is safe to use in every circumstance I am aware of.
But I'm not an expert by any means. I've used it. Seemed to work very well. But I have not proven that the Melafix was the real cause.