Suggest Treatment For Constipation In A Child

Dear sir, my daughter is 5 years old and she is suffering from constipation problem, doctor was suggested laxopeg half sachet every day for one month. we have given for 3 days but we observed that abnormal size of her stomach, her stomach was little bit big rather than normal, its some like filled with gas. Even though she not complaining about that but we are concerned. Please kindly suggest whether to continue laxopeg or not.