An elderly lady, with bakcground of coeliac diease, hypertension, type 2 diabetes mellitus, mild cognitive impairment, ischeamic heart disease with 1 previous coronary stent, was initally admitted 5 days ago with productive cough, shortness of breath and fever. She was diagnosed to have community acquired pneumonia, and was given intravenous antibiotic for the treatment. Patient was slowly improving clinically. But, she complainted of having increasing in bowel motion, mostly waterry loose stools around 4-5 times a day since yesterday, with minimal abdominal discomfort. Patient is a known patient with coeliac disease, and she is compliance to gluten free diet. How would you investigate her diarrhoea ?? What will be your treatment plan??