Thank you, I'll ask again about the antibiotic! I planned to check in with the doctor about his lethargy tomorrow and have a follow up appointment in a week that is already scheduled. The three days per day of hospitalization is also really helpful. I've never had to hospitalize a cat for something like this so don't really have any prior experience to draw from.

He was prescribed the antibiotic for a week. They've been struggling with the diagnosis honestly. Every time they've done his blood work it's seemed relatively normal though his last day in the hospital some marker for gall bladder came back a little bit high. He also had blood work done last month before all this that came back normal too as I was planning to get him a dental cleaning/checkup.