Several months later, I'm finally going to tell you what happened with "A Cat Named Mike". My apologies for not doing it sooner...life got in the way, and for awhile I wasn't blogging.
Anyway.....We got Michael to the vet, and his liver values were high. For a few weeks, we kept Michael isolated from the other kitties. His liver values could indicate a chronic liver condition, bad food from the outdoors, or an infection.
Michael also had fleas and ear mites. We took care of those two through the normal means. His limp was likely caused by a misshapen growth plate when he was very little (and being kept in a confined outdoor area with his mother).
We put him on a stable diet...no luck with the liver values. So, we tried antibiotics...
He is now happy and healthy, and officially part of our Clowder some seven months later. He's a wonderful, well-behaved and adorable cat. He's just over a year old.
Sorry to keep you all waiting! :)