Hi welcome to the health care magic She has been diagnosed stomach cancer as per history.. Now, this dry cough could be from acid reflux or viral infection(including influenza) might be the possibility... For dry cough she had given good drug that is cough suppressant dextromethorphan... Vitamin C lozenges also can be prescribed (having viricidal action) Use warm water for drinking If acid reflux present than pantoprazole like antacid drug prescribed.. Your medication history also should be taken as certain drugs can lead cough as side effect.. If problem not relieved than chest x ray taken for further work up Take care Consult physician for examination