My Damara lamb would always get bloat if she went straight from green grass onto the bottle, or straight from the bottle onto green grass. She'd make a beeline for it too. I fixed it by preventing her from having green grass for at least half an hour before an after a bottle. But Damaras are desert sheep and yours, I'm guessing, are not. Still, might work! Definitely, mixing fresh green grass and milk always caused bloat in her.
Now she won't eat green grass at all. Hay and random preferably toxic weeds and trees, but no green grass. Her breed are classified as browsers like goats, not grazers, and as I understand it many ancient (and some European heritage) breeds are also classed as goat-like in the feeding style.... Your bloaty one may be like that, not really built/bred to graze?