I've taken this in the past when my headaches first started and before they were diagnosed as migraines. This is Butalbital which if I'm not mistaken is a form of Phenbarbital, Acetaminophen, and Caffeine. When I looked up the side effects it did say it may cause constipation, diarrhea, epigastric distress, heartburn, nausea and vomitting. I hope your Dr. can give you something to help you out better.
Sandy