Is It Safe To Take Metrogyl For Amebiasis,constipation And Gastritis?

Sir,Since the age of 24 I m suffering from acute constipation &excessive gas problem. I also had abdominal pain but not since last 3yrs. I was treated as patient of Amebiasis or colitis.Blood , urine stool & barium meal x-ray were ok. Now ,at the age of 65 I m mentally upset for not getting prmanent relief even after prolonged treatment.Now a days Tab.metrogil -400 is prescribed for10 days at regular interval.Pl.guide me for proper treatment.Regards, B.S Bhatnagar( Male)