Well here I am with another food question

As some of you may or may not know, I switched Tatum over to Natural Balance Potato & Duck Small Bites (Allergy Formula) almost exactly a month ago. For the past few days she seems to have totally lost interest in this food - which I might add is SO NOT like Tatum, lol. She is normally my little piglet and will usually eat any and everything you give her. However, it seems that now this food just isn't cutting it for her anymore

I hate it too, because she has been doing really well on it so far and doesn't seem to itching NEAR as much as she used to. Tatum has VERY bad allergies and I just need a food that she will eat, and one that is going to help her.
So ok, here is my question. The other day I went into the place where I buy my babies food and I got a sample of the Natural Balance Potato and Fish Allergy Formula food and gave it to Tatum today for the first time and she seemed to absolutely LOVE it. Now, I don't know if it is just because this is a new food and it's something a little different that she is liking for "the moment" (it's so weird even saying that, cause she normally IS NOT my picky one, that would be Stedman, lol

) - BUT, she seems to be more interested in this Sweet Potato and Fish one even more than she was with the NB Potato and Duck initially.
So basically I am just wondering if anyone here feeds this (NB Sweet Potato and Fish) to their babies with allergies and if so, what are your results with it? How long have your baby(s) been on it and do they LIKE the food? Are they itching any less?
Sorry for the long post but I just wanted to explain everything

And thanks in advance to help help that you can offer!