I hate to say it, but perhaps if you left it too late with your dog and the other two sheep you mentioned, trying to treat yourself via the internet, then the vet didn't have a chance to save them.
Unfortunately big operations on animals cost money (google the chap who compared the cost of cruciate surgery in himself to his dog for a more realistic idea of what value for money vet operations actually are!) and you would have been told that there is always a risk of losing an animal when operating or the few days after. If the vet was willing to perform the surgery, its because they thought the dog had a chance of recovering. We don't do surgery on animals that are going to die anyway to charge owners money.
Sheep are prey animals so they try to hide illness so as not to appear weak. This means when you see they're ill, they may not have a lot of reserve left before they die. Thus you need to get correct medical treatment for them quickly. It also makes it extra hard for the vet to diagnose as they really hide their pain and other symptoms.
I hope for her sake that your ewe is not suffering while you find a new vet.