Water and poop?

Hi everyone. Maybe you can help me since google isn’t. Whenever I drink water, like down it cus I’m thirsty, I have to poop right away. My stomach will cramp, and gurgle, then I have light diarrhea. Do you guys know why this could be happening? Def will ask my dr for more detail, but I’m just wondering your opinion. In order for me to stop it I have to take some metimucil (fiber supplement)