My dog, Sparky (Shih Tzu) is 3 years old. He scratches himself constantly and occassionally will chew on an area of his skin where it's bothering him, usually around his butt/tail area. He started doing this about a year ago or so. I feel so bad for the dog because he does it during the night too. I rarely see a flea on him. Currently, he is eating Purnia Beneful mixed with Eagle Pack Holistic Select Anchovy, Sardine & Salmon Meal because I'm changing to a different brand/type of dog food. So, once the Purina Beneful dog food is gone, I'm going to feed him the Eagle Pack Holistic Select Brand. I can't afford the most expensive brand of dog food on the market. Is there anything I can give him that would help him not scratch so much?