My one-month old grunts non stop and cries like he is constipated, but he is having normal yellow, seedy stools. Could something besides gas be wrong?

It's normal. It's normal for babies to grunt and fuss when they poop. It's really hard to go to the bathroom while laying down! you can massage his stomach from the right side to the left in a clockwise fashion and bring his knees up to his tummy to help. Giving probiotic drops can also help with gassiness. If he is unconsolable or acting like he is ill, take him to his doctor.