What type of food do you feed her?
How long has this been going on?
Does she have episodes of diarrhea as well?
Has any medications ever been tried?
Does she continue to eat even when she is having these episodes?
Is there ever any hair in the vomit?
I feel that your girl may have inflammatory bowel disorder. Stress definitely can be a factor as well as diet and allergies. I suspect the vet has put her on the w/d to help with her vomiting. I would consider switching this over to a low allergen diet like Hills Z/D. Cats can be sensitive or even allergic to a component in their food like chicken, beef, wheat, or corn. Removing some of the offending allergens helps to reduce the inflammatory response. Sometimes there is no cause found to this disorder but minimizing as much as possible and reducing stress has been proven to help. Many cats also need prednisone during flare ups and some need to go on this on a more long term basis to keep the inflammation down. Hopefully, we will not have to go this route. The pinkish color is very possible blood as a result of irritation to the lining of her stomach from vomiting or possibly the coloring in a snack or treat. I recommend giving her 1/4 pepcid daily to help settle her stomach.
Diagnositic tests would be an xray of the abdomen to look for thickened intestines, bloodwork to rule out hyperthyroidism (common in a cat this age) and to rule out other underlying illness like kidney and liver disease and if you want to go so far or if she does not improve potentially endoscopy for a biopsy of the stomach.
At the very least I would recommend the bloodwork to rule out hyperthyroidism and kidney disease.
Here is a link on inflammatory bowel disease and potential causes and treatments.
Please let me know if further assistance is needed.
Yes, this is the human pepcid.