Allergies...They run in the family

Most of you know that we have been battling Abby's severe allergies since we got her 2.5 yrs ago. Recently I changed her food to a very high quality (& expensive)dog food called Blue Buffalo. I got her the lamb & rice flavor because that supposed to be less allergenic. She has done great on it, her skin started to clear up & her coat has never been softer or shinier. I highly recommend this dog food to anyone. I had to take Izzy to the vet the other day d/t the fact that she kept scratching at her ears & was yelping some. You will never believe what the vet told me.....Izzy is having an allergic reaction to the new food!!! UNBELIEVABLE! This is a new vet since we have moved but I really liked him & he was very honest. After telling him about Abby & her problems he recommended that my dogs be put on a strict diet for at least 4 weeks to see if they did better. They can't have any chicken, beef, lamb, corn, wheat, or rice. Do you know how hard it is to find a dog food that doesn't have some form of one of those in it? I was going to make them food w/venison, potatoes, & veggies but you need to make sure they get vitamin supplements if you do that & every one that I looked at had at least one "bad" ingredient in it.
So after literally 8 hour on the computer looking at dog foods, the ingredients & Internet forums, I finally found something. Taste of the Wild dog food, it has one that is made from fish & potatoes. There is also one called Natural Balance (@ Petco)& they have a few different flavors for the dogs. They are also pricey but they are @ the same as the Blue Buffalo. The other reason that I had originally changed their food is because all the crap (fillers, preservatives) in regular dog food. My mom has had 2 dogs die from cancer & it is becoming more common so I wanted to try to avoid this with my 2 babies.