Hi, I'm sorry Youre going through this with Opie, and I hope he feels better soon. If he just has a tummy bug, it should clear up in a day or two. It's okay to not feed him a couple of meals or to feed him a bland diet to give his tummy a rest, but don't restrict his water, because he has diarrhea and vomiting, and you don't want him to dehydrate. Is there any chance he could have have swallowed something?, that you're not aware of like a piece of a toy? Keep an eye on him and watch for signs of an obstruction, such as the vomiting, diarrhea, lethargic behaviour, or drooling water from the mouth.
My male Dozer has swallowed socks on 4 different occasions, and a dish cloth, and he only showed signs of an obstruction on one of those occasions, he ate, drank, and played normal. He was always able to either poop them out or throw them up, it took one of the socks a whole month before he threw it up. If he continues to vomit, I would take him to the vet and have him checked out. Please keep us posted on now he's doing.