My hammy's acting weird)):

[PeanutsMom]

How old is your hamster? Make sure that the temperature isn't too cold or above 80 degrees. If it is above 80 degrees it's too hot for him and that could explain everything. If its too cold he may be going into hibernation. If the temperature is good then he might be depressed or maybe he hurt his back somehow. You could call your local vet and see what they say over the phone and then take it from there.

[Whisk_Luva]

If he is old then maybe he is slowing down, thats what it sounds like to me.

Hibernation also sounds like a possible.

Either way I would call your vet.

[Hellow]

It sounds like he is just wearing out. I don't believe there is any reason to be concerned. But, if you are still worried, i would call your vet and schedule an checkup.