Digestion problems

Question
Hello, I have a 1 1/2 year old yorkie/jack russell mix. Recently she has developped a digestion problem. She frequently had diarrea and throws up at least once a week. I took her to my vet several times and $600 later all they could tell me was she has a sensitive system. They put her on special food and I mix rice in with it to help. Lately she has lost her appitite and eats ALOT of grass. Her stomach also gargles alot. My bank account is kinda maxed out so I would hate to take her back to the vet to spend another 300 and find out nothing. They did xrays and blood tests and stool samples on her. all results were normal.
any ideas?

Answer
Hello, I'd like to point out some sensitive systems dog foods contain only fish and poatatoe this is suitable to be fed without adding anything, also lamb and rice is said to be good for dogs with sensitive stomachs, dogs eat grass for the same reason as cats to sooth there stomachs(it can also induce vomiting I've noticed)...think nothing of the grass eatting if anything its helping her stomach, sorry I cant be of more help but we've not had a stomach problem to date.