Hi Ubba!
Sounds exactly like A's recent poo problem. Stop dairy and see what happens. He was always fine with it then suddenly couldn't handle it. Maybe R is having the same problem? I know how horrible it is when they're in pain it's just awful. Just keep an eye out to make sure there is no undigested bits of food or if it's really smelly as that can be a sign of Giardia.
Hope her little bot bot feels better soon xxx