Question: I have been suffering from severe bloating, constipation, and diarrhea for the past five years. When I go to a regular doctor they always want to put me on an antidepressant. Naturopaths advise fiber and probiotics, but nothing seems to work. I tried Cymbalta for a few days and quit because it poisoned my body. The fiber and probiotics give marginal help. Thyroid? Depression? Stress?

Dr. Hibberd's Answer:
Any change in bowel habits, especially with alternating constipation and diarrhea, must be professionally evaluated. Under most circumstances, an irritable bowel can be assumed and treated while an appropriate workup to exclude more serious conditions is initiated.
Serious conditions include malignancy, infection, inflammatory bowel diseases, and electrolyte disorders. These conditions require more than symptomatic treatment, and must be looked for to be discovered.
Be sure you have had suitable blood work: usually a CBC, CMP, Amylase, Lipase, and ESR in conjunction with suitable stool cultures, stains, and analysis for blood, bacterial toxins (such as Clostridium difficile enterotoxin), stool analysis, etc.), and pathogens.
By all means be sure to have a colonoscopy (a scope examination of the entire large bowel) with biopsy to exclude structural large bowel disease. If your source of loose stool is still unidentified, you may need further investigations of absorption, small bowel function, and possibly upper intestinal endoscopy (scope of esophagus, stomach, and small bowel) with biopsy.
Though antidepressants may help some with irritable bowel symptoms, they are to be used only as an adjunct to specific treatment. This off-label use of anti-depressants should be explained to you by your consultant, and if used should be part of a comprehensive treatment plan, not a stab in the dark.
It appears you have been a recipient of "shotgun" therapy. It is time to take responsibility for your treatment, and insist on a full and proper investigation, so your treatment can be more effective and possibly even curative.
Fiber does help reduce many irritable symptoms in patients with bowel irritability, and does tend to aid bowel movements. Probiotics may have a role in replenishing bowel flora after protracted antibiotic treatment, but have no role in chronic use that we can ascertain.
Request a referral to a competent gastroenterologist if your present doctor is uncertain, and let me know how you do.