Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. IBS or SIBO is a diagnosis that is made after all the relevant investigations of stool, blood, urine, CT scan of abdomen, colonoscopy and upper GI endoscopy are within normal limits. Since you have not mentioned the age and gender, it is mandatory to undergo colonoscopy to rule out colon cancer as alternating diarrhea and constipation are one of the symptoms of cancer of colon. If all the investigations are normal then you have to do the following: Control of stress and/or anxiety. Identify the foods and beverages that cause such problems and avoid these fully. Take the medications as per the symptoms and if there are no symptoms you may not need a long-term Fibercon, and so on. Stool tests helps a lot in getting the correct diagnosis. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T Chandrakant