I agree with both the above posters. She's getting older now and these things happen. Too many changes in her life would be extremely hard on her. Has there been any changes in her food? I'd ask your Vet... it might be time to change her to something else. I know I can't tolerate some of the foods I used to - maybe she's going through the same thing.
Good Luck! I hope you can get this resolved before the new puppy arrives.