I have a 6 week old baby who is currently taking Similac PM 60/40 but he has not had a bowel movement in the last 2 days. He seems to be trying but just can't. What do I do?

I have an infant child that is 6 weeks old and has not had a bowel movement in 2 days. He is currently taking Similac 60/40.

I'm no longer familiar with infant formula. Is it iron enriched?

Definitely change the formula,It took four changes of formula for me. I went from Advance to Spit Up to Soy, finally I put my infant son on Similac Allimentum and within hours I saw a change. He was a totally different, happier baby boy who made a bowel movement withen hours too. Good Luck!