My bunny in question is coming up for 4 years and has used the bottle just fine but today he seems to be turning his nose up at it. I know that he ought to be thirsty because he has been confined to his enclosed part of his hutch while the weather was bad but obviously he isn't drinking today. I'm not sure if he drank or is drinking when I'm not with him. His partner is eating and drinking just fine but this one is not. What should I do?