All Proteins shakes are not equal, I found some shakes upset my stomach and I am not even post surgery yet!
From a nutritional website:
whey protein isolate is the highest percentage Protein you can buy. Whey protein isolates are typically about 90% protein before manufacturers add in flavors or sweeteners. That means there's little room for anything else. As a result, most whey isolates are fat-free, are very low in carbs, and are lactose free. This makes whey isolates ideal for those dieters trying to dramatically reduce carb consumption or bodybuilders trying to cut-up right before a contest.
For kids or adults who are sensitive to the small amount of lactose found in whey protein concentrate, then these lactose-free whey isolates are an ideal choice. From a taste standpoint, compared to whey concentates, whey isolates have a more watery consistency and tend to taste slightly better.
A typical serving of whey isolate contains about 25 grams of protein, 2-3 grams of carbs and 0 grams of fat. Try the clean, refreshing, light taste of whey protein isolate.
Maybe take a look at the types of shakes you have tried, although you have tried different brands it may be the same kind of protein and additives. Good luck!!