I've just read your posting having been at Crufts for three days. I'm sorry to hear that Rosie is ill again.
Re Shelley's advice - dogs often used to be fed on just himan left overs but of course we don't have so much of that nowadays. I agree that what she will eat let her eat.
There was a dog food I noticed at Crufts which was a mixture of rice, herbs green veg and meat of course (no kibble) cooked and just required to moisten it with water before feeding. The developer was explaining that acid foods were bad for dogs and that they should be fed on alkaline food. The explanation was believable. I wonder if that would suit Rosie? If you're interested I'll get more details.
Did you try the Osmoinds supplement? Is it worth contacting Frank to find out whether the others from the litter had similar problems?
Do you think a probiotic might help?
Do let us know how things went at the vets, please.