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in children occurs if they are low fibre diet and junk foods.
Give your child diet rich in fruits and vegetables.
Give her lot of water to drink.
Ask your kid to play a lot running around and do not allow him to sit infront of the computer or television.
Children will have decreased appetite particularly after a episode of fever
. Encourage her to consume more and do not force feed her.
Continue to ask further queries as required.
Hope this helps.