She throws up anything she eats and says it tastes bad. She is only eating a little fruit, but is given like a pedialites. she is on lots of medicines for diabetes,high pressure. but she cant stomach those much either, She says her stomach hurts, the doctors dont know what do for her.
Are you witnessing this, or is she reporting it to you? The self-reported of dementia patients can be very unreliable.
Have you taken her to a gastroenterologist? Or to the ER during one of these episodes? Has she had an endoscopy (had a lighted tube put down her throat to see what is going on)?
If you are in charge of her care, I would get her to the ER right away, as Pam says. But I suspect that you are not being told that she has some sort of life limiting condition.