As Elusive says, if he’s only been back in his old room 3 days it is a change again and personally I would give him a couple of weeks of being left alone until he’s adjusted to the environment the cage is in again. After that he should start coming out more of his own accord. So just keep talking to him meanwhile. Then see how things are in a couple of weeks. Talking to him is the start of taming again and if you see him out, maybe offer him a treat through the bars.
It’s usually time and patience. Until he gets his confidence back and gets used to your presence and voice again fully.
It’s surprising how much a room change can affect them. Even with a very tame hamster I’ve had for a while they can take a couple of weeks to adjust and start coming out normally again. He may adjust quicker if his cage is where it was before.
He’s also having to adjust to people changing as well since you got back from holiday.
If he burrows down under his house then it’s more a case of waiting to see if he starts to come out more naturally over the next couple of weeks.
Then see how things are then
When I mentioned taking his house out - that was me racing ahead and assuming everything else had been done first so I wasn’t quite clear there.
First thing is give him a couple of weeks settling in time and not disturbing anything during that time. I’d also hold off on any cleaning for a while as well. Does he use a litter tray for peeing (if so you can just empty that every few days - if not you can just spot clean the pre area occasionally).
Have you seen the cage cleaning guide on the home page?
