Severe Diarrhea vet not helping- need 2nd opinions

My 10 week old bengal is having severe diarrhea minutes after he eats anything. It’s extremely liquid- he was also throwing up but the anti nausea stopped it.

He farts and poop comes out and he leaves poo everywhere, we have to bathe him constantly bc he has no idea he’s releasing it and his butt is extremely red. The vet gave him bland food and probiotics and a deworm tablet and it’s gotten significantly worse over 72 hours. His fecal samples had “no eggs” based on the in house test. I’m so lost