Is It Normal To Have Loose Stools, Weight Loss, And Digestive Issues After ERCP, And Could Vyvanse Affect This?

Had gallbladder removed in March 2023 and ERCP. Did good. In July 5, 2023 started same terrible pains and acute biliary pancreatitis due to stones and sludge left in common bile duct. Had another ERCP August 2, 2023. Been on low fat diet and having loose stools since August 8th and have lost 20-25 lbs since July 11th and today is August 18th. Stomach still queasy and gassy. Is this normal? Temps been 100 degrees every day so hard to gain weight with heat in Louisiana and low fat diet. Also, would 20mg Vyvanse effect anything?