Don't forget that 'Hypoallergenic' dog food is only hypoallergenic if it doesn't contain whatever your dog is intolerant too. Chicken is one of the biggest culprits, is beef, so maybe try a food without those to start with and see how you go?

James Wellbeloved is one of the better completes, and they do a grain/cereal free one now, but if you can afford it, and want to feed complete, Orijen is the best you can buy, in my opinion.