I sent an email off to my vet clinic describing it and asking if it sounds like something that should be looked at, so hopefully we hear back from them tomorrow. What gets me wondering is that he is 100% unbothered by it, and it's not red or anything. No wounds or discharge, just black flakes/crust and I've seen flies there. I read that fly strike happens pretty quick (like a few hours), and I feel like I've seen these spots from a distance at least since a couple of weeks ago, and I've definitely seen flies there a month ago and more.