Grunting/reflux AWFUL at night?

STM, but I don’t remember having this issue quite as bad with my first son.

My younger son is 5.5 weeks old and EBF - he sleeps in his bassinet during the day and for the first part of the night with no issues (i.e., minimal spit up and no grunting whatsoever). However, after his first wake up/feeding, he will grunt and squirm for HOURS until I finally bring him into bed with me. I know about infant dyschezia, but I have been giving him mylicon and honestly the grunting doesn’t stop once he does pass gas/poop. Additionally, it seems like he’s squirming so much that he’s aggravating his reflux to the point that the sleep sack and bassinet mattress are soaked. I try to burp him during and after feeding, hold him up for 30 minutes afterwards, have his bassinet elevated on one side with risers, cut out dairy for a while, etc. but it seems to make no difference.

I also don’t get why it would be so much worse during the night when he doesn’t seem affected at all during the day? Also, why can he lay flat in the bed next to me and suddenly stop grunting/having reflux? Wondering if there’s anything I can do differently to help because my husband and I aren’t sleeping at all and I also just feel so bad for him. Do I just have to wait for him to grow out of it?!