My mother in law has been ill for a month today. Feeling very tired.Loss of appetite?

My mother in law has been ill for a month today. Feeling very tired.Loss of appetite ,when she does manage to eat a little she heaves and brings up frothy spittle. As a consequence of this she is becoming confused. She has had two trips to the hospital. she has had 2 ecg,s , 2 x.rays and 2 full blood counts and all came back normal. A doctor from her local surgery came this week and gave her some anti sickness tablets but nothing seems to be helping. She is 91 years old