Have you tried some baby massage in the evening and wearing him in a sling in an upright position for some of the day? Both can encourage pooing. My dd liked a poo after she'd been in her tummy tub too
My DS was just a dramatic poo'er as well. Think it stopped when solids started, certainly remember it a lot better then. We also had a wee vibrating bouncy chair which seemed to help a bit when he was puffing and panting and straining. Think some babies just do this.
Try giving him a warm, deep, bath - take him into your bath, it's lovely!
Try lying or cuddling him on his back, curling his body up by lifting his knees to his chest and then opening up again. Do it several times. Also bicycle his legs. This seemed to help our dramatic pooer, and also released trapped wind.
You could very gently massage his belly in a clockwise direction. Very important: only clockwise.
It will ease with time. He's just getting used to a working gut.
Glad to hear that this is all quite normal, but what do you do with him for three hours of inconsolable yelling and squirming? He's so so loud
I can't decide if picking him up or leaving him down is more comfortable for him (he hates both) or if I'm just making things worse... will try the bicycle legs, but actually he kicks so violently I don't think he'll let me... we also have a vibrating chair I can try when he's like this.
MW today at the bf clinic has suggested clockwise tummy massage at nappy changes (but not when he's having an episode) so am going to get some oil from the chemist this afternoon to try that.
DD used to do that - but she was about 12 months old so maybe not comparable. Anyway, turns out that DD was not struggling but holding. She had torn herself with a hard poo (according to the the specialist) and feared poo's ever after.