I wouldn't treat the fish with antibiotics just yet, I don't see any signs of a bacterial infection. Antibiotics have side effects in aquariums, so you only want to use them if trying to treat a specific infection.
Did I read that the fish ate well for you then? I think it is just adjusting to your tank.
I'm still struggling to understand the timeline here - ich spots can't just show up and certainly not when you move a fish to a new tank (there would be no tomites in the new tank). In looking again, it looks like detritus/dust to me. Let use know how the fish looks this morning.
Jay