I took my hamster to an Emergency Clinic for Animals here in Madison and they were very good with her (although she didn't make it). They did say they do rabbits. I have also been to Healthy Pet Veterinary clinic here in Madison (they're open on Saturdays I think) with a hamster and I really liked them, may take my rabbits to them sometime. If you think you need a rabbit specialist in off-hours I know the UW-Mad vet school does do off-hours consultation. You just call, a vet tech calls back to determine the severity, and they will have a specialist come in if you need them to. It can be expensive. It does sound like he needs to see a vet soon. Maybe someone is open on Sunday?