What Causes Foul Smelling Watery Stools?

Hello,
I have unique problem.i have foul smelling stools and i am unable to pass motion completely and also there is a sensation of stool comming out after bathroom upto 1 hour of passing motion and even there is sensation of fluidic substance comming out.due to this alot of bad smell comming out if me.i am not able to go to college due ti this smell.also i have noticed white mucus in stools and colonoscopy done result says normal.please provide solution