Girls, hello ? We're only a month in and I have such a question, for t…

Girls, hello ? We're only a month in and I have such a question, for the last two days, my child is only going potty in a diaper. But on the big one he refuses, cries a lot and can't go, as if he can't. Then he cries from this very much. We still have colic now. As soon as I take off the diaper, within two minutes he starts pooping on the diaper, and calms down. Now I started freeing him up during the day so he could go normally on the big one. Maybe someone had this? Suggest what it might be.?