Agree with Jenn and Jenah....I do recommend grain free, don't think Nutro is. An allergy to chicken is quite common.....Now I will add one other issue, that is more common to gsd's, but can be an all breed issue, just more common to gsd's, and that is EPI, if your dog is throwing up, has diarrhea, and is unable to gain or maintain weight, or is losing weight I would ask your vet to test for EPI. I would feed a one protein only grain free kibble, look for something with lamb only, seems to be a pretty easy digested protein for most dogs, if after 4 or so weeks on that type of food, then I would suggest the epi test or rule out sibo, another tummy issue similar to epi.