Newborn strains to poo but not constipated, normal poo. To a point where he starts crying. Also grunts alot at night bedtime. Is this normal? Thank you

Normal. Newborns can make a lot of funny noises, including grunting, especially with gas. Having a BM can be a lot of work for a little one-- weak abdominal muscles, lying you can help him--put him in a sitting position (gravity), pull his legs up (imagine yourself trying to poo lying flat with very weak abs!) Rub his tummy, and a warm bath might help. If not better, see your pediatrician!