After reading through this thread, I was going to ask if the medication was flavored. Most medications are not manufactured for rabbits, so it isn’t unusual for them to come flavored to entice dogs. Hopefully getting a sweet version will help.

I’m sorry to hear your other bunny is unwell. This isn’t something you want to hear, especially after losing Adi. I agree with the others. This is likely something that has been building for some time and it was just the stress that made it visibly symptomatic.