DS is 1 month old and gets pumped milk in a bottle. For maybe the past week or so he will drink half of it and then for the rest of the bottle will grunt and strain and look like he is in pain, trying to pass gas? I make sure to burp him really well but he still does it.

He seems fine about a half hour after the feeding and will nap for 1.5-3 hours. every once and awhile he will have bad gas during his nap and cry in his sleep and then I hear him pass gas.

I guess I'm just wondering- does this sound like there could be an issue with my milk? Does this sound like a milk protein allergy or something? Or is this all normal?