These previous sitters may not know what it feels like to be in your situation. Unfortunately I do. It’s upsetting to have a pet go through anything medical but the blame game never makes it better. Anyways! I agree with calling Rover to find out how they can help. This is why pet care companies have insurance, plus they may be able to facilitate communication. The less you have to interact with her directly, the better. Finally, Please stop feeling guilty! This is not your fault, the dog is not in any pain and you did your job well. We can only control so much. Best of luck!