My puppy is 10 weeks old and she is constantly biting her hind legs around her knees and chewing on her legs. She also bites her feet too. She on Purina puppy chow but I just bought her Wellness to switch her to. Ive read about using vitamin e or salmon oil on her food. But I wasnt sure if you can give that to a puppy or how much to give her. Shes whining ALOT from all the itching so I need to know what to do. Thanks.