Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today.
Based on your history, it does sound like she may be eating the pellets and causing herself a gastritis. Though given her previous GI concerns, we cannot rule out that Patti has IBD, a bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections or GI lymphoma (though less likely if she is only 3).
With this all in mind, we can try some home supportive care to try to settle her stomach. To start, if she hasn’t just vomited (since otherwise we’d need to rest her stomach for a few hours first), then you can consider treating her with a OTC pet safe antacid. [ie Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac), Tagamet (More Info/Dose Here @ http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet)]. Whichever you choose, we’d give this 20 minutes before food to allow absorption. Of course, do double check with your vet if she has a known health issues or is on any medications you haven't mentioned. Though if you give this and she cannot keep it down due to nausea that is usually a red flag that we need to bypass her mouth with injectable anti-vomiting medication from her vet.
Afterwards, you can consider starting her on an easily digestible diet like cooked white rice with boiled chicken, boiled white fish, cottage cheese, scrambled eggs, or meat baby food (as long as its garlic/onion free). Or if we do get her settled, her sensitive biscuits may still be an option. The aim of these diets is that they will be better tolerated/absorbed by the compromised gut. Therefore, it should get more nutrients in and result in less GI upset. As long as improvement is being seen, I usually advise continuing this until the signs are settled, and then weaning her slowly back to her normal diet.
Since dehydration is a risk if Patti is vomiting, we need to keep an eye on her hydration. To check that she isn't dehydrated, there are a few things you can test. Further to checking for gum moisture, do make sure she doesn’t have sunken eyes and that she doesn’t have a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a good video HERE (http://www.ehow.com/video_12232503_dog-dehydrated.html). If you are seeing any signs of dehydration already, then that would be our cue to have her seen before this becomes an additional issue for her (especially as it is often dehydration that makes them feel unwell).
Overall, her signs do raise a few concerns here but if you have just put sheep pellets down then that could certainly attract her to eat them and cause GI upset. Therefore, we’d want to start supportive care to settle her stomach. If she cannot keep that or water down at any point, appears dehydrated already, or doesn’t respond to the above within 12-24 hours; then we'd want to get her vet involved. They can assess her hydration, make sure this isn't related to previous GI concerns, and start her on injectable anti-vomiting medication +/- antibiotics to settle her stomach, and get her back feeling like herself.
I aim to provide best care for you just as I do for my own clients & their pets. If you have any other questions, please ask – I’m happy to help but please rate me with the **STARS** (or leave a written rating of 1-5; 5 being great) as this is the only way I am credited for my work by the site & this allows me to continue to help here. This is included in your question fee. Once you rate, your question will not close & you can still ask follow-up questions. Thank you. : )**