My Zarita does this quite often. She has reflux though. She is on Pepsid from the vet for 'acid tummy'. She is my problem girl when it comes to being nauseated in the am. She acts like a 'pregnant lady!!!' Sue Davis
Dary used to have empty stomach syndrome, but it was definitely yellow and smelled like bile. You could try giving her a little snack at bedtime. Dary also took sucralfate once a day, and that seemed to help.