Chicken allergy and introducing to raw?

Please help. My friends addopted a one year old staffy. He was on dry food, they wanted to switch him to raw. Before that did, he developed some tummy issues, he had diarrhoea for few days, so the vet suggest chicken and rice diet. Every time he had it he was sick. I suggest it could be allergy. And to start the raw introduction with fish( cod) or turkey. They switched the food but now he got very red patches and scratched the to the point they bleed. The vet gave him steroids and his better. They are afraid now to go with the raw diet. I think the dog was just going through detox but still think his allergic to chicken. What would you suggest?

i would suggest leaving all poultry out & start with a lamb diet (plus, of course, liver & other offal - all from lamb). try that for a couple of weeks & if all's okay try another protein, such as fish. the only reason i put fish second is that you can't buy fish liver/offal, which is so important for a raw diet, so if you start with lamb & that's okay you can carry on with the lamb offal, with fish as the main food. don't forget that, even with fish, bones should be included.