Poodle stomach issues

Does anyone else’s have a poodle with really bad stomach issues? My dog is usually vomiting at least a couple times a week, and the vet couldn’t figure out why. Asking here in case anyone knows why 😭

Edit to add that it’s been happening since he was a puppy. It’s getting to a point more recently where I’m struggling to handle the issues, and I have to consider rehoming him with his stomach issues being one of the reasons why (not the only reason)