lisaj0908 depending on how old the hamster is , he or she is teething and it's painful ,so the find something hard to know on, so the pain can be avoided!

Well, he probably got in a cat fight or got a little painful wound on/in his pad, so you should call a vet  - take him to the vet and see what's going on!

Depending on how much you play with the dog and give attention to the dog...if that's not happening then that's probably it and/or the dog might be depressed or something similar to that. Or the dog could be experiencing a discomfort problem?