How To Treat Constipation Inspite Of Taking Metamucil And Miralax?

I have Meinere s Disease and also a H Pyloric elevated acid level. Recently I have had more digestive problems than usual, i.e. leaning toward constipation. My stools have been dark, blackish green for the past few weeks. I have stomach discomforts as a rule. I ve been taking metamucil or miralax or a miralax Sams Store substitute. I ve started to wonder if my Gall Bladder could be involved? I am 82 yrs old.