Hello. I Have Been Plagued With Periodic Constipation For Many

Hello. I have been plagued with periodic constipation for many years. I am taking Metamuil twice a day now and that has helped substantially, but my question is this: my stools are not normal looking! They are a long strand of a large round stool attached to a thin line of stool and then another large stool attached to a narrow stool... and that continues for one long bowel movement. The stools seem to be tarry. It's an embarrassing question, and I've asked my doctor, and he didn't seem to think that was abnormal. But I never had this until this past year. Before then, the stools looked normal. Can you tell me what you think of this?