My girl Tabby has been a bit off recently. I've never had a kitten so I need a little help please? (Plus cat pics)

Hi everyone, my cat Tabby is acting weird. I've never had a kitten, I normally have older cats. She's salivating a lot recently which smells foul. I looked up online and it could be teething problems. She's 10 months old. I'm going to the vets first thing Monday with her, but is it something I should be worried about?

Tabby getting stalked by the local Romeo. http://i.imgur.com/Y6Tk7.jpg

Cats! http://i.imgur.com/iuGqD.jpg