recurring food allergy

Hi

My year old cat Chloe is allergic to fish. Several months ago she developed a funny growth on her lower lip, a 2 inch narrow rash on her right back thigh and between her toes, she also had terrible gas and diarrhea. We took her off fish and the symptoms soon went away. Apparently her symptoms are A-typical of such an allergy.

Now we have her on hypoallergenic dry food and keep an eye on her wet food for fish products. Then I came home from being away for several months with a goldfish in a bowl. I caught Chloe drinking out of the bowl and now the allergic reaction is back. I am assuming this is from the "gold fish soup" she ha s been enjoying so I put a screen over the top of the bowl. However I am also concerned that the makers of her wet food have switched their ingredients to include a fish product.

I am going to switch her to another food and keep an eye on her, but meanwhile she seems to be bothered by the reaction she is having, often tugging at her rash which is now scabby. Does anyone know of something that will decrease the itchiness, but won't harm her if she licks it off?