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Loose motions with pain in abdomen can be due to infection of the intestines.If you are not pregnant and if you are not allergic to any of the medicines then you can take tablet-Oflox-TZ 1 tablet 2 times a day for 3 days which is a combination of Ofloxacin
both antibacterial and antiprotozoal.Also since it can cause acidity and nausea
you have to take antacid
tablet like Zinetac-300 mg along with the other tablet.Drink enough water to maintain hydration.