Welcome!
My best guess; Food intolerance. There's something entering your body regularly that's toxic to it. Worse than a food allergy, this condition actutally damages the small intestine to the point that nothing can absorb, resulting in nutritient deficiecy and dehydration.
Regular doctors are totally useless, in my experience, in diagosing food intolerance. I also went to numerous and had lots of tests, even a barium test. My condition was finally determined by a
GI panel test with a
Registered Dietician (more than just a dietician, this is like a doctor of dietary issues.) I'm intolerant to cassiene (protien in diary) and soy protien. I'd unknowingly eaten these things for so long, they damaged the scillia in my intestines. This caused ANY food to go right through me, even a glass of water, at times. Intense cramps and gurgling in my gut leading to immediate bowel evactuation within moments. I remember pulling over on the side of the road to go- like you, there's no stopping it. It was totally debilitating.
You're literally eating somethting that is poisonous to your body. You need to find out what it is ASAP. Do not try "food elimination" diets. It takes too long to figure out what the culprit is bc your gut is so damaged.
Good luck! Keep us updated!