I have been having acute constipation ever since my family doctor put me on an antidepressant that only caused weight gain. The constipation seems to be getting worse and I m starting to have dark, almost black, stool. I drink plenty of water, eat a healthy diet that includes a daily probiotic, and exercise on a daily basis. I have been messaging my doctor, but not getting any help. Her solution is just to put me on a different antidepressant, which I do not need.