need help with mysterious gastro problems

I'm a 48 year-old who exercises regularly, been a vegetarian for 20 years, always normal weight.  I've had loose stools my entire life  but the past few years there has been a gradual change in bowel habits.  Now I experience constipation and what feels like incomplete bowel movements.  More recently I've been diagnosed with reflux and hiatal hernia (after endoscopy).  I am experiencing stomach pain with no relief from bowel movement - which I would have had in the past.  I am a very anxious person and I know that there very well could be a body/mind connection.  Also significant is a history of migraines with a lot of aspirin and codeine usage for them.
I had a colonoscopy last year that was clear except that the doctor did mention that I was especially twisty/turny (whatever that means).  I have had 2 c-sections so adhesions come to my mind as a possible reason for the gastro changes but I'm very concerned about cancer.  Any ideas?  I do have another doctor appt. soon.