[Pebbles82]

I think it would be good to get a vet check as it could be a number of things - a back injury can cause problems with back legs as well. Although you didn’t mention if it was front or back.

Yes free roaming is good for them, but heights aren’t. They climb up and can’t get down again so they drop and can get injured. So best to supervise feee roaming, make sure the room is hamster proof. A room with floorboards is rarely hamster proof unless you have very well fitted carpets and even then there can be a hole round a radiator pipe they could squeeze through. Thirty odd years ago I didn’t know much about things and we had a hamster that used to climb the curtains to the top. I shudder to think now! But he survived amazingly.

Of course if you block off an area they try even harder to get there! Contrary. But maybe try blocking the gap to the back of the bookcase. I have one corner of our lounge fenced off by a piece of hamster playpen (wood) and a lap cushion wedged behind it. They could probably get over the cushion if trying hard enough so I just watch and keep an eye on things.

You could even set up a large playpen area which is popular on here - and put a spare wheel and some toys in and hide treats. He’d probably enjoy that but might want to be out after a while if he’s used to free roaming.