At that young age, he is probably so small that his breathing shakes his little body a bit . Luna was like that when she was little, but it’s only noticeable now as an adult after she has been running around. What’s your weather like right now? Overheating becomes a concern around I think 80F? Cold water and the cool ceramic tile are good ideas. For the oscillating fan, just make sure it doesn’t blow directly on him.

Signs of overheating include fast breathing, shaking, lethargy, breathing through the mouth, and hot and/or red ears. To address overheating, cool your bun down immediately but gently. Do not put him in ice cold or cold water because he might go into shock. Instead, give him a couple light spritzes of cold water over his body. Since buns regulate their body temperature though their ears, take a cool wet cloth and dab his ears with it. You could also put some ice in water bottles and set it next to him.

I know you said you don’t think he’s scared but he could be stressed, my buns tend to sprawl out after a while of being stressed (in the carrier when they’re off to the vets) as it takes a toll on them.

Hopefully you can figure out what it is Bet he’s a tiny lad!