The reason the blue is so prevelant is because your camera "sees" more blue than your eye does and captures that. You can adjust the white balance on your camera to make up for it, but don't ask me how. lol I just don't know.
On to something I do know about. In the first pictures, the biggest splotches are absolutely stress spots. This second picture could still be that but I'm not 100% sure. I wouldn't suggest treating with antibiotics unless we are relatively sure it's an infection. Reason being, they can build up a tolerance to them and we want them to work if we need them later. For now, I'd suggest vitamins like Vitachem or Selcon in the food, Lots of nori, very clean water and lots of hiding places. Let's see if we can keep the stress to a minimum and boost his immune system at the same time.
I'd like to know if you did two rounds of prazi and how far apart they were, as well.