Well, you'll have to talk to the vet no matter what, because they are prescription foods. The vet may have samples you can try to see which, if any, agree with her.
Also, there is another company (I forget the name) which sells prescription foods in the pet stores, usually right along side the Hills foods. Our cat is on the Hills k/d (for kidney disease), and we've sometimes given her the equivalent in the other food. We don't anymore, because the other brand seems to disagree with her... but their equivalent of an allergen-free food might work for your dog.
If none of those work, you might have good luck with some of the foods others here have mentioned. You may just have to keep trying until you find one that she can handle. And there are lots of recipes out there for dog food if you want to delve into making it yourself. Doing that means you would be able to tweak until you get something that works best for her.