My sister's GSD had similar problenms and they eat Victor dog food now. there are many different formulas. You could look into that. Its cheaper than Fromm and I say better.
Victor was one of the first brands I looked at and the fiber is too low for my dog. He would have anal gland issues within a week. We're trying out Zignature. It's nearly $20 more expensive than what I can buy Taste of the Wild for at my local feed store, but since it's higher calorie I'll be feeding quite a bit less and that should help make up for the cost increase.