[gmacleod]

I don't think my reply is going to be of much help to you, I'm afraid. What you're describing doesn't sound much like anything I've come across before, whatever the dog is fed.

Is she showing any other signs of pain such as panting? And how is her colour (check her gums - are they nice and pink, or are they white?). Not wishing to lie down certainly sounds as though something is making her very uncomfortable. Conceivably something is stuck somewhere, but that's really something a vet is going to have to sort out I'm afraid.