Hi Eswara Kumar, Welcome to HealthcareMagic Forum.
If he is passing stools once in 3 days, he is suffering from Constipation
. May be you are not feeding him with proper diet. Kindly take him to a Pediatrician
so that he can examine and rule out the exact cause for Prescribing Medications. Give him Plenty of fluids and water and fiber rich foods like fresh fruits and Green Leafy Vegetables.