Advice needed

My LO is 6 weeks old. Since birth he's always had trouble passing wind/pooping easily. At first I brushed it off and thought he was just trying to figure it all out. After about a week of him constantly screaming, I pushed for an ultrasound - everything came back clear. Does anyone know how I can help him pass his wind ? He's not constipated, he does poop but it's the pushing that hurts him. I've done bicycle legs, tummy massages, colic stuff, infants friend. someone help. Old remedies , new remedies , herbal. ANYTHING