Extreme nausea, vomiting, and diarrhea every time i workout too hard. im 28 y/o male in good shape. symptoms last 20-30 mins. why is this happening?

GI symptoms: With these symptoms, it is pretty clear that you're doing something your body doesn't like. The most obvious suspect is that you're working out too hard and putting circulatory stress on your body, particularly your GI tract. When you exercise, all your blood flow goes to your muscles and away from your GI tract, which can cause GI symptoms. Cut the intensity of your workout by 50% and build back.