Well, Carson is back at my place. Tuesday night, I met a family interested in adopting him, and I saw that he had some white bunny snot he'd sneeze out of his nose, as well as a slightly sticky/wet butt. So, he came home with me and saw the vet on Wed.
Carson is doing well, less than happy at having to take Baytril, but otherwise his old self.
I swear, they have it so good my house that they put their little bunny brains to work plotting ways to come back here. I have a few people to call who are interested in adopting (probably him, but not sure), so hopefully he'll be on his way to his forever home soon.