It sounds like you might have Constipation Predominant-IBS. Chronic constipation is often cured by natural remedies: A diet with natural fiber from fruits and vegetables, at least eight cups of water a day, and exercise -- plus maybe an occasional laxative from the drug store. But if natural remedies and over-the-counter medications don't help, it may be time to ask your doctor about prescription drugs.
Have you tried Miralax (OTC)? When used according to label directions, Miralax produces a bowel movement within 12 to 72 hours. I would definitely try that. It's not a stool softener or a stimulant laxative, so won't cause severe pain and cramping as Dulcolax can.
Another option is to use Lactulose which is a prescription. Commonly prescribed for chronic constipation.
There are some NEWER prescription options for IBS-Constipation such as Linzess. This drug is a capsule taken once daily on an empty stomach, at least 30 minutes before the first meal of the day.
Amitiza, is approved by the FDA for the treatment of chronic constipation.
Hope this helps.
Dr. Riaz, Doctor of Pharmacy