While I'm new here and I don't have much personal knowledge of digestive and bowel disorders, one thing I do know is that constipation can be a symptom of an endocrine disorder, such as Hypothyroism.
If you have other symptoms like feeling tired, weak, or depressed, dry skin and brittle nails, not being able to stand the cold, memory problems or having trouble thinking clearly, and/or heavy or irregular menstrual periods, you may want to talk to your doctor about it.
Screening for thyroid disorders follows a simple blood test, where your TSH levels are measured. There's a good article on iVillage about it at: http://www.ivillage.com/hypothyroidism-1/4-o-88527
While I'm not a medical practitioner, I just thought that you should know that constipation is a common symptom. Maybe it can provide some insight.
I hope this helps! Good luck,
Thanks for your help. I actually went to my GP about 10 years ago and that was the first thing they told me. They put me on Meds. and I have been on and off for years now. The reason I am on and off is because the docs said my levels were normal and I did not need it any more. I may have to go back though. Funny things is that even while taking the medication my constipation problems did not change a bit.