Lose motion happening after every month, it may be because of some sort of the food in digestion or food allergy Give the less quantity of the milk and more focus on other feeding

Stop bottle feeding.

Do USG abdomen pelvis

First and foremost stop bottle feeding; as baby has crossed 1 year, start introducing baby to his/her own plate with spoon. Encourage baby to self feed Secondly give more attention to hygiene of the baby and regularly clean his/her toys, because babies tend to put everything in their mouths. Thirdly give nutritious food which should include various fruits and vegetables on daily basis Even after all these measures if baby continues to have loose stools please consult

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