Talk to Pediatrician on Digestive System

Please tag any paediatrician.. my baby is one month old.. after birth he was admitted in nursery and had high antibiotics ..

now problem is that he pushes too much after every feed and it feels like he wants to pass stool and he is constipated, (but actually he is not) and he constantly cries during this time .. when i see his diaper, i find nothing ..

at the other hand he poops fine when he does .. he is on motherfeed so he passes stool on alternate days .. and stool doesn’t feel constipated..

Now I am unable to understand why he cries and pushes too much and behaves constipated when he is passing stool fine