You have not mentioned about your diet though. A healthy and full of fiber diet is also necessary for bulk formation as well to facilitate bowel movement. Lactulose
is also known for its intolerance. .Also colofac
is known to cause bloating
in some cases.I would suggest you to stop colofac and take healthy diet full of fiber, prokinetics orally twice daily,Drink plenty of oral fluids and juices take fibrous fruits without peeling them. You will soon be normal.