Talk to Pediatric Gastroenterologist on Severe Constipation

Hello doctor, my son is 2.5yr old. he's suffering from severe constipation from past 3 months. i have tried every remedy and laxatives. even used glycerine suppositories . in beginning suppositories helped him in passing stool but now they're not working. consulted a doctor and he prescribed micronema. enema helped him at first but now its also not working. due to this problem i can't make him potty train. hes pee train just. remedies and medicines used: laxoberon, sikilax, milk+desi ghee, almond oil, castor oil belly massage, one strange thing is hes good at eating. eats almost 3 times a day with 2-3 feeders of milk. im really worried about his condition. hes becoming weak day by day. please suggest something for him. thanks