I have a 7 year old GSP and today when i got home from school i gave her a milk bone. I heard her yelp really loud so i ran over to see what it was. I looked her over (feeling her paws for splinters,ETC) and she was fine. Then i was watching her and whenever she puts her head down and opens her mouth to eat her bone she yelps in pain as she bites it. I looked at her teeth and it didn't seem like there was anything wrong. Im no vet so i have no idea whats going on. Please help!