Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
I am so sorry to hear that your gal is not feeling well. My first thought, considering her age, is that she may have the beginnings of Kidney Failure , which is treatable when caught early. Vomiting is the first sign and the color you see is due to excess bile showing up in the vomit. I would strongly recommend that you have your vet examine your gal and run blood work to rule out any metabolic issue. If this is ruled out, then your gal is suffering from a mild digestive disturbance causing intermittent nausea. The treatment for this is as follows:
Fast your gal for 12-24 hrs to allow the digestive tract to calm down and heal.
Give her Pepcid AC or Famotidine at 0.5 mg per pound every 8 hrs. That can be purchased over the counter at the pharmacy.
Give only small amounts of water during the fast or ice cubes
After the fast, feed rice and boiled chicken (2/1)
If the vomiting has resolved, then wean her back onto regular food. If the vomiting persists especially during the fast, take your gal back to your vet for another exam and lab work to determine the cause for this. This is extremely important since this can cause dehydration or other more serious concerns such as Inflammatory Bowel Disease.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please REPLY so I can clarify for you.
Sincerely, ***** *****