Koko has similar issues from time to time. She will start eating grass while we are on our walk. She will then throw up the grass and yellow mucus from her stomach. i will give her Pepto and she will usually perk up after that. I can usually tie her upset stomach to something she ate the day before. We found that eating any meat, that we normally eat, will upset her stomach. If she gets into the cat food it has the same result. We just have to watch her very carefully because she will eat anything. I have had to pull cotton out of her mouth, that she was trying to eat, where she had pulled the stuffing out of one of her stuffed toys. I feed her a Nutro food that has oatmeal as one of the ingredients. Oatmeal is suppose to help dogs with sensitive stomachs,