Talk to Pediatrician on Constipation

My baby is 3months old and having severe constipation. Its been two weeks now. Only suppositories and enema is helpful. Doctor prescribed me vidalyn and ferosft which are i think for iron but he still told us to give it to the baby. Another doctor prescribed me digas drops and colibid drops. Nothing worked. I have tried massage exercise gram sikai and gripe water. Still no result. Later on we gave him skilax drops.He is totally on mothermilk. I am also drinking a lot of water as people told me to drink more water. What should i do? Any other remedy to relieve constipation beside enema and suppository.