If its bloat they would be rolling around, going to lie down then getting up, stretching their back legs out as if you would if you had gut ache. Generally uncomfortable. It could just be that they are eating a lot of grass and getting fat. We brought in 6 of our tame lambs from the field last night and their stomachs were very full, they were like barrels, but a night in on hay has brought them down to normal size. You could give 40ml of oil just to expel any gasses in their stomachs that have built up as a precaution and give them some hay but if they are out at grass they probably wont touch it.