Nin just brought Norrington back from the vet, and he got a clean bill of health. He's 8-10 weeks old, he's a little underweight, but didn't have ear mites. The upper respiratory infection is normal for a stray kitten, and the vet thinks it will most likely clear up on its own. They had a kitten package that includes all his shots and a free visit, and the blood tests and such for $265, so Nin went for that. They'll give us an estimate for getting him fixed after he gains some weight. Apparently he was the delight of the office and quite the little attention slut. Oh, and she says he's going to be a BIG cat when he grows up.
Such a relief! Two of the last three stray kittens my mum rescued didn't make it, so I was a wee bit worried.