Add probiotics...
Don't rob your body of quality protein by consuming some overly hyped cheap protein powder just because it works with your stomach.
Try introducing digestive enzymes to your regiment, just add them into your protein shakes. These enzymes will not only promote intestinal health, but they also help protein assimilation and can aid with breaking down the nasty by-products of protein synthesis.
You could always try a protein that already contains digestive organisms (acidophillis, bifidus, yogurt...) like Dorian Yates Pro-Peptide or V3S Vitapro.