It could still be just individual differences, illness and meds, Robyn, but worth looking into. In my limited experience, even if a condition is said to only affect one breed, a dog is a dog is a dog, at least genetically, and any canine malady can strike any individual. That being said, though, he's on some pretty powerful meds that may well be affecting his development and appearance (the 'pred head' you mentioned, for instance).
the vet can set your mind at ease. Holy catz, if it's not one thing to worry about, it's another, eh?
Good luck on Monday!
