Doc told me tht i have ibs gave me prebiotics but still my soft stools haven't improved. and i also had e coli intestinal infection?

IBS: I would doubt E Colin as a cause. Generally speaking this is either an acute infection or associated with a change in location where there are differen subtypes of E Coli in the environment. IBS is a diagnosis of exclusion. You should be tested tor parasites, celiac disease, IBD food allergies. Try increasing your dietary fiber intake and see if it helps