Model Deforming When Animating

[Nemix]

ok i tried to do some animations for an oozaru...
like walking i put him in the pose i wanted then i wanted to put his head strait and his arms in the pose i wanted to but when i rotated theyr bones the model deformed... the head got bigger and the same at the hands...
could someone explain why?

 

[Doormat]

Try this in the Rotate tab

 

[Nemix]

Thank you Doormat!