I have a steer that is pot bellied. He has been that way since I got him at 8 months old. I thought he was wormy. I have wormed the you what out of him and he is still pot bellied.
When he eats fresh pasture you would think he was bloating or just about to calve, it's kinda a combination of the two. He will have more bellie on the Right side like you see in bloat and be as wide as a short legged cow due to pop. If you pull him off pasture and wait til morning he will look okay, still pot bellied but not bloated looking.
With your animal if this large stomach is not normal I would get a vet out asap. When it has not eatin much food that day how is the stomach? Still large?