Hello, my name is***** and I have over 20 years of experience as a veterinarian.
I am very sorry to hear about your pup's excessive drooling, eating grass and vomiting.
Dogs with nausea or gastroesophageal acid reflux often eat grass or foreign material to make themselves vomit. They will often swallow repeatedly and lick things trying to soothe their nausea and acid burn. If they vomit once and can rid themselves of whatever is irritating their stomach that way then all is good.
But when they are vomiting repeatedly and continue to be uncomfortable then we need to stop them from eating any more grass. It becomes a vicious cycle where the more they vomit the more their stomach acid burns their esophagus and the worse they feel.
Possible causes of vomiting and nausea causing grass eating include a change in diet, dietary sensitivities or allergies, or eating things that they should not like too many fatty table scraps or garbage, bones etc. Addison's which is a poorly functioning adrenal gland is another possibility for waxing and waning vomiting and nausea. If she's a younger pup metabolic organ failures (kidney or liver disease), pancreatitis, inflammatory bowel disease or even infiltrative cancers are possible causes but less likely.
Has she eaten anything she should not have recently (toy pieces, bones, garbage)?
Any changes in food or treats?
You can give her acid reducers to try and settle her stomach. Either:
1) Pepcid-ac (famotidine) at a dose of one half of a 10mg tablet per 10 to 20 pounds of body weight every 12 hours.
2) Prilosec (omeprazole) at a dose of one half of a 10mg tablet per 10 to 20 pounds of body weight every 24 hours.
These will reduce stomach acid and should help settle her stomach. These can be used for several days if necessary as they are very safe.
I'd also pick up her food and water for now. A couple hours after one of the acid reducers is given you can offer small amounts of water or ice cubes to lick. She's likely thirsty but we need to settle her stomach first.
No food for 12-24 hours. Small amounts of water only.
After her food fast then start a bland diet of 1/3 boiled, lean hamburger (or boiled, white, skinless chicken) and 2/3 boiled white rice. Give small meals several times a day. Feed the bland diet for several days until she seems back to normal, then start mixing in her regular diet and slowly convert her back.
If her vomiting or nausea continues then she may need injectable medication from a veterinarian to get her stomach upset under control.
So watch her for continued vomiting even with the acid reducers, blood in her stool or vomit or a fever (more than 103.5F rectally), a tense painful belly or lack of appetite after her food fast. If any of those occur it is time to seek hands on veterinary care.
Please let me know if you have any further questions.