Yup, sounds exactly like "almost-bloat" - good description!
And yes, sheep can and do get bloat. Especially going onto fresh, red-clover-rich pasture.
If you get one affected worse than others you can often help by massaging the flanks. (Left hand side, where the rumen is.) If not improving and stomach wall feels tight, get the sheep penned on some clean ground so you can see if it's pooping. If not, or if discomfort is worsening or stomach feels really hard, look up bloat drench on here and give it some. (Basically a liquid mix of natural yoghurt, veg oil, and ginger. Add sodium bicarb just as you are about to administer. And stand back, belches and farts usually ensue!)