Hi Jo, thank you for replying. No, Matilda doesn't have a temperature. We have been back to the vet for xrays since my post, and the vet thinks that Matilda has a malignant cancer. They have ruled out Addison's after doing a Base Cortisol test, and are having her back tomorrow for a specialist abdominal scan to see if they can find a mass, and are also doing a special blood test for something called parathyroid...something or other - I can't remember what it's called, but it's like a hormone that will show whether or not there is malignancy in her body. She is still very bright in herself and is back to eating normally. So it doesn't sound like an auto-immune disease, but does sound like we will lose her to cancer