Before I was more educated on dogs, I used to feed whatever the petstore employee would say was best. I was feeding my dogs a chicken-based dogfood for a long time and I thought the itchiness was due to something other than food (afterall I was feeding them the best!). As soon as I switched over to Lamb based dogfood (healthwise but now Natures recipe) the scratching stopped. You may want to try that. Problem is, dogfood starts to get so expensive so Lamb/Beef may cost a little more but eliminating the side effects is worth it.
I have a feeling that the current itchiness is due to flea bites considering they are trying to make a last attempt at my dogs before it gets cold. But I would like to try to eliminate any skin itchiness that I can control. Problem with adding oils to dogfood is upsets digestive systems. I will look into it and if I can find something on my own I will post it here.
"The greatness of a nation and its moral progress can be judged by the way its animals are treated."
- Mahatma Gandhi