Hey, Include whole grain foods, fruits and vegetables in you and your child’s diet. Avoid dairy products ,offer high fiber containing diet . It is important for children to keep themselves well hydrated. If a child does not drink adequate fluids, she is more likely to get constipated. Mild osmotic laxatives ,stimulant laxatives are helpful. I cannot prescribe medicine here moreover  vomiting will not be there in constipation, she may have GE consult pediatric doctor