Oh Bisc! You certainly are one for keeping your mum on her toes aren't you?
When I first saw this and knowing Bisc's hip trouble I thought 'he's suddenly decided the lip of the tray has become unmanageable for him.' This is what happened with Mimzy after his tilt and because of his spondylosis. But you said he'll use it if you move it from this one area. :?
I've never nebulized a bun so I can't speak to that however Mimzy has become a very wary and scary bun since his own ears and eyes have begun to fail. He has cataracts and is almost blind in his up eye. His hearing is all but gone. Touching him in any way without first blowing gently on him elicits his flight response and some thumps/foot flicks for good measure. I would agree Bisc has some disorientation going on since a bunny's ears give him so much information even just as far as balance is concerned. Perhaps he is bowing because he feels about to tip or fall? Has he been moving about a bit slower and checking his surroundings more, i.e. mental mapping?
Maybe keep some notes or a video of this new behaviour and take them to his vet when he is next seen...or ask them to advise you in the morning.
Worry is our way of taking extra care not to miss anything important, but remember our bunnies pick up on our feelings very easily. Try to take a cautious but optimistic approach for both your sakes. It's so hard, I know. ((((((((Huge hugs)))))))))
xxxxxxx
ETA: My daughter would be grinning from ear to ear to hear that Bisc doesn't like spiders, she doesn't either! :lol: That would be her kind of bunny!
