[Nancy's Hamsters]

If this just started with the new wheel I would wonder if it isn't him being territorial of his new possession? If it continues may want to have a Vet look at him as sudden change in temperament could be an indication of him having pain and no way but biting you to alert you that something hurts(If he has been running in the new wheel a lot it may be his muscles are aching from over doing it). Is he peeing a lot more or just drinking more? Wheel running will work up a thirst.