I am 42 year old maleand I was passing stool on frequent basis from last two or three days, some times it was in okay form and sometime like a water, I had to go to toilet 7-8 times in a day, Doctor prescribed me o2 medicine and after two days on medication my condition become better but now from last two days I am passing black stool,I am still on o2 medication , I also have a incestional hernia in stomach which occured due to gall stone operation.