Thanks for all the input Growler! Roxy had skin scrapings done on October 22nd the vet didn't find any parasites, nor any fungi, abnormal bacteria, or yeast. I was looking at peas and kelp too mainly. I have to get her back onto the Iams and not so flared up before I start testing again. This is such a slow process. It will probably be 3-4 weeks on the Iams before I will test an ingredient.
Marty, I had no idea such a test existed. That is brilliant. I will call my vet to ask about it, thanks!
Here are some pics of her toes at the worst...I have been cleaning them with a mild Hibitane solution in the evenings so they are much better now. Notice in the first one the creamy stuff in between her toes. It looks like degradation of the skin (infection starting?). This is mostly gone now I have been cleaning. Pics are from the 11th just before I cleaned them the first time.