I just had my revision from Sleeve to Loop DS/SIPS/SADI two days ago. I was having your exact symptoms BEFORE my surgery from the powder protein shakes. I was using Bariatric Advantage, Vanilla, which is why I logged in today to see if I can return 75% of the bag. Those shakes made me feel horrible, constipated and bloated, WITH diarrhea and all the other symptoms you described. I stopped doing the poweder protein shakes from Bariatric Advantage, and switched to similar count Protein/Sugar/Calories/Vitamins, made by Slimfast. The chocolate flavor was divine after drinking down chalk for 5 days! I bring all this up because this all happened BEFORE the surgery, and it was because of the powder protein shakes. Add Benefiber to every shake, or take Colace twice a day to get you back to normal. Or better yet, switch to the Slimfast Advanced Nutrition High Protein ones. They taste 1000% times better and no horrible symptoms, but you still need the Benefiber or Colace bc of the High Protein. Sent from my SM-N986U using BariatricPal mobile app