Hi and welcome to Healthcaremagic. Thank you for your query. I am Dr. Rommstein, I understand your concerns and I will try to help you as much as I can. Yes, these are definitely side effetcts of excessive lactulose and laxative use. First step is to stop using it immediately. Then you should find alternative for constipation management: . You need to increase fiber intake. Good fiber sources include bran and other whole grains found in cereals, breads, and brown rice, vegetables such as brussels sprouts, carrots, and asparagus, Also, you should exercise regularly. Moving your body will keep your bowels moving, too. Second, you may at times need to try other rmedies such as as Fleet Phospho-Soda, Milk of Magnesia If there wont be improvement on these measures, you should consider doing diagnostic tests such as colonoscopy, anal sphincter manometry and food allergy testing. I hope I have answered you query. If you have any further questions you can contact us in every time. Kindly regards. Wish you a good health.