Dog Itching?

I know this has nothing to do with this app... But I took my dog out and he usually comes when I call him at the door. I had to go outside and call for him. He came. But once he got inside he started to shake and itch his head none stop. His balance is a little off too.. What does that mean? He's never done this before and I can tell its bothering him a lot. He's 6 months old and a golden retriever mix.