Help moms

Its currently 5am and been up all night cus my 3yr old is in pain cus he cant poop... I've tried to give him Miralax I tried other things massaging him what can I do he has been up all night in pain

Er suggested to give him Miralax and nothing else

EDIT: THANK YOU ladies still up at 7am... just got back from the store he wont take the prune juice still up and crying he was ok at the store tho idk pray hes okay im worried and we get to sleep soon 😭