Moms, Please answer! 😭😭

Abi
My 4 month old baby hasn't pooped in two days. I know it's normal but he usually goes everyday. He looks constipated, grunting and turns red when trying to poop. But he couldn't 😓 It makes me cry as he looks so uncomfortable. And I'm kinda scared. But his wet diapers are the same. He's exclusively breastfed. FTM here so I'm not sure what to do. Will be calling his pediatrician this evening. Just want to know whether this is normal and how to make him poo.