itchy and red area

Hi guys, I recently got a Boston Terrier that suffers from allergy symtoms (redness on his face and belly + itchy eyes). I have put him on an elimination food trial by feeding him a pure duck food and planned to do this for 10 weeks. Now, after 3 weeks, the dog found the cat's food and ate...

So, for the past few weeks, my dog has been itching her neck really often. I checked her neck when she first started doing it and it seemed redder then normal. When I showed my mom she didn't see anything so it went nowhere. As time has gone by I stop my dog from itching her neck when I catch...