My husband is having is having problem in completely emptying of stool. So he feels gassy at night due to which he is often getting sleepless nights.he feels urge to empty bowel. After emptying (quantity is sometimes more or less) he feels relaxed and sleep. But this struggle is long to disturb night. He had peptic ulcer twice once in 2017 and then in 2018. His stool is soft and not hard. He is drinking around 5-6 litres of water daily. What could be the reason.