The first thing I would suggest is for you to have your vet run some allergy testing to find out exactly what is causing this problem. You can read a bit about allergens here:
http://allergies.about.com/cs/canine/a/aa072699.htm
If she is chewing herself bloody, I would be concerned about an infection brewing, so please make sure you stay on top of that aspect. :)
There are typically 2 types of allergy testing done. One is called Intradermal Skin Testing. Basically they mark spots on your dogs skin and on the spots they place a possible allergen and check the spot in about 2 days to see if there is a reaction. The other is a Serum Based Test. Definately do the Intradermal Skin Testing first as the Serum Based test is not 100% accurate.
You can read more about the testing here:
http://www.petplace.com/dogs/allergy-testing-in-dogs/page1.aspx
It seems you have waited long enough before switching diets as results usually show in 30-60 days. I have had positive results using Eagle Pack Duck and Oatmeal with my dogs and dog that come into rescue with allergy problems. To find an Eagle Pack retailer, check out their website at:
www.eaglepack.com
Without knowing exactly what is causing the allergy it can't be properly treated so give your vet a call and discuss the testing so your baby can finally get some relief soon :) Hope this helps send you in the right direction and good luck to you and to your boy :)
__________________
**Although a deposit was put down, I, PERSONALLY, don't get paid until you click the
Accept button..your deposit remains with Just Answer**