Are you sure that the Hot Spots were caused strictly be an allergic reaction to her current food? Could it be possible that it is not food related?
http://www.vetinfo.com/dallergy.html...od%20allergies
How long have you lived in your current place and were there any changes made recently in your surrounding area? (Example: new carpet, new flooring, recently had new landscaping, etc.).
You may want to consider getting a comprehensive allergy test done, just so that you are 100% sure of what is causing the problem.