Yes, food could cause certainly cause digestive symptoms. Have you tracked when he has symptoms and what his last meals were before the symptoms? That can be very helpful in figuring out causes. What foods are you feeding him? Have there been changes to his diet recently? He's probably on something very low-carb because he's diabetic, is that right?
My thought on the Proviable would be to wait to give that to Marvin once his gut is a bit more stabilized. Some cats may have symptoms from probiotics if they don't start on very low doses. (I've made that mistake myself with one of our cats!)
I'd very strongly suggest speaking Marvin's vet. Maropitant is a great drug for our vomiter because it keeps her from vomiting. But it also has a tendency to reduce appetite in some cats. I've heard of Buprenorphine but have never used it in our cats.
I hope Marvin starts to feel better soon.
My thought on the Proviable would be to wait to give that to Marvin once his gut is a bit more stabilized. Some cats may have symptoms from probiotics if they don't start on very low doses. (I've made that mistake myself with one of our cats!)
I'd very strongly suggest speaking Marvin's vet. Maropitant is a great drug for our vomiter because it keeps her from vomiting. But it also has a tendency to reduce appetite in some cats. I've heard of Buprenorphine but have never used it in our cats.
I hope Marvin starts to feel better soon.