Severe constipation with GM develop, Delay

21 months old male child, weight 6.2 kg with h/o constipation x 10 days, GM age 5 months, FM n Speech 12-15 months, h/o develop. Delay in elder sibling CNS : DTR; brisk, plantar b/l down.

Sensory normal, higher center normal P/ A:  fecal matter palpable Rest s/e ; wnl No p/h/o similar complaint Laboratory:: CBC; 6.4/9000/2.3( mcv57) TSH n fT4 : normal Current issue is patient is not able to pass stool after giving enema bd since last 2 days along with syp. Lactulose, milk of magnesium So kindly suggest me wt  next to do for constipation..