Why Is My Toddler S Severe Constipation Persisting Despite Medication?

My 4 year old girl having little bit constipation problem sjnce birth but from last 6 month constipation problems are big. She is not passing bowl for 7 to 10 days. Whenevergave her creamfin that she doing potty.Hi dr suggest ezlax 2 time and piclin at the night for 3 days.i gave her but shi is passing bowl movement from 8 days ..whg this is happened