Try putting her on a probiotic supplement such as Culterelle, or other over the counter acidophilus combo, and a digestive enzyme such as Wobezyme, or over the counter equivalent. Use 1/8 to 1/4 human dose and frequency if you find a human product.
If these are ineffective she may have food allergy gastritis and switching to a hypoallergenic food may be effective, but you should do this under a vet's care.
Thank you for your comment, but my dog doesn't throw up every day or several times a week. It's nothing that serious, for if it was, I would have taken her to the vet long before now. I was just wandering if anyone else whom owns a Shih-tzu has had this same problem and what they do about it. All I can say, it that when she does this throwing up, she usually will not eat anything until later on in the day, if at all until the next day. It's as though she throws up and afterwards she'll be fine. Again, thatnks for your comments/info given in your reply.
The yellow froth is just bile - the natural contents of the stomach when it's empty of food. What you need to nail down is why she's vomiting on an empty stomach, and for that you need a vet visit. She may just have a ticklish tummy that needs some pepcid once in a while to keep her right, or there may be some underlying disease that needs to be treated.
Have you been able to tie the vomiting episodes to anything like too much people food or any medication? That info will help your vet with a diagnosis. Any regular vomiting needs to be looked at, and no breed is more prone to vomiting that another, so go ahead and make that appointment.
my 18wk old shih tzu does the same thing any help? its very worrying thanks sarah