I was not braining well this morning!
besnoitiosis!
It's a protozoan type parasite (Besnoitia darlingi) which sadly has no known way of treating it. Cattle can carry a different species of it as well.
Supposedly, cats don't seem to show symptoms of infection, but in opossums, they get encapsulation cysts everywhere. You can really see them inside the ear, along his tongue or there's one on his cornea that we've been keeping an eye on too. Who knows how badly his insides look though given he's got them everywhere else.