All of these are signs of a rabbit that’s in pain. He may have gas, a broken/twisted nail, dental problems, sore hocks, you name it. I know he prob won’t like being dragged out, but it may be necessary if you want to check him over. Rabbits recover pretty quick from hating people; mine absolutely despise getting their nails clipped, but are back to being friendly the next day. Its better to have him hate you for a few hours than to have him sick.

How is your bun doing now?

I agree with DV, when a normally friendly, social rabbits withdraws to under furniture etc, it is as a rule a sign of pain. Sick rabbits tend to hide away so as not to show any vulnerability to predators that might come around. This is a deep instinct with rabbits.

If he has gas pain you can fgive simethicone baby gas drops, 0.5-1 ml every hour for 3 hours. It often helps quickly. It’s not taken up by the body, it just acts locally in the GI canal, then gets pooped out. It can be found on the baby shelf at Walmart, Tesco etc.

It is important to feed a bun even if the bun hates it. It’s normal for rabbits to fight meds and syringed food. It’s actually good when they do, because that shows spirit and strenght. A really sick rabbit just sits there. Many of us here have had the experience that rabbits not only “forgive” you once they feel better again, they can actually seem to like you better than before.

Could your other rabbit be bullying him? If you’ve had him a month (which really is such a short time for him to settle an bond (gas might have been from all that stress), and he’s been sick in that time, so it could be likely your other bunny is sensing that and causing some problems when you’re not looking. It could be why he wants to hide a lot. Usually it’s best to wait for new buns to settle before bonding because it is quite stressful to change environments then rush right into bonding. Even in well established pairs, if there’s an illness it can lead to problems. The hiding is really what makes me wonder.