There is the possibility this could be an ear problem. An ear infection could cause pain while your rabbit's chewing, which your rabbit could be trying to change head position to try and stop this from happening. And a face that looks swollen on one side, may not actually be swelling from a dental issue but swelling from an ear infection pressing on the facial nerve and causing paralysis and facial drooping on one side of the face.
So if you're seeing one side of the face drooping or having a swollen appearance, I would suggest an immediate visit to the vet to get your rabbit checked for a possible ear infection, which may require xrays if it involves the inner/middle ear. And maybe to recheck the teeth too while you're there in case there is just something stuck in the teeth or a developing dental issue.
Medirabbit, ear infection in rabbits
Is the panacur for deworming, or is your bun being treated for e. cuniculi, and if so what symptoms made the vet think this?
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