I Have A Maltese, Phones, 13 Year-old, She Woke This

I have a Maltese, phones, 13 year-old, she woke this morning with heavy belly breathing. She is lethargic, has taken very little water and no food or treats. I called her vet, he thinks she maybe fighting a bug, I think she is about to pass away. Is there anything more I can do for her?