What Causes Inflammation Of Abdomen Along With Vomiting Up Of Yellow Mucus?

For the last two months my mother has experienced multiple symptoms that have been diagnosed as Gastritis. She wasn't given anything for it and was told by the hospital it would go away after a month or so. They performed an endoscopy as well as tests on her kidneys since there is low function. She is diabetic and has just started a low dose of insulin. Her symptoms are inflammation of the abdominal region with a lot of pain in the rib area and under her breasts, vomiting yellowing gel substance and foam, cannot eat and when she does she has severe pain in the abdominal area afterwards, sleeps all the time and has lost over 20 pounds in the last month. Her magnesium level also keeps dropping but we aren't sure if it's related to this. She does not drink.