Breast cancer and side effects of medici

Hello Doctor, My mother was diagnosed with breast cancer in Dec 2016. She was operated to remove the right breast along with the lymph nodes under the right arm. In order to give the chemotherapy we did a port insertion. Till now she has completed 4 major chemo with 3 weeks interval and 12 minor chemo on weekly basis. Later she had 25 sessions of radiotherapy. Now at present she is taking on doctor advice, endoxan daily and folifrax on weekends. Recently she is suffering from acute gastritis. As a result she feels nauseating and does not recover with oral medicines till she is admitted and medication for vomiting is given through IV. Please advice on the same and also if there can be any changes in the diet that can help her during nausea. We eat veg and nonveg.