It's definately not scale rot. It's to dry and clean for it and it's on his back, scale rot begins on the belly.
My BP had this also. I was at the vet (for some shots against worms etc.) and I let her look at it. It's caused by a difficult previous shed or treatment of the skin with some substance. As you said he had a bad shed and you coat the spots with a triple antibiotic. That's why the scales are coming off like this. Nothing to worry about, just keep the humidity up for his next shed and he will be fine.