Can A Stage 2 Duodenal Cancer Patient Take Gelusil For Chest Burn, Indigestion, And Bile-like Vomiting Before Starting Chemotherapy?

Can cancer patients in 2nd stage (poorly differentiate carcinoma in Deodenum 2nd and 3rd part) take gelusil as after having meals he is having chestburn, irritation,indigestion, feeling like all the food is stuck in his throat and also have thrown up(green bile like vomit with food particles) in past 3days....He will be having his first chemo next week.