Sorry to hear about your mother's problem. She is suffering from metastatic breast cancer
, which has already spread to the lungs and the doctors are suspecting spread to the abdomen as well.
At this stage she is a candidate only for palliative chemotherapy
and hormonal therapy (if the cancer is ER, PR positive).
To confirm the spread to the stomach, a biopsy can be done, but it is not going to change the line of management. She can be given acid reflux medicines by the doctor. The lack of appetite
can be explained due to wide spread cancer.
I would suggest that you consult your oncologist
and palliative care
specialist. For pain management, you can go to a pain clinic.
Hope she feels better after the treatment