Seen my dad do this wuth my cousin, lie him out along your arm on his tummy and hold his chin, the baby was so relaxed and loved every.minute of just lying therw
My first baby had "silent reflux" where she was never sick or had the acidic breath but did display some of the behaviour your talking about. She would take ages to feed,arch her back after,refuse to lie in a cot or moses basket n was very u settled at night.took a few months to get a diagnosis as her symptoms were similar to other things like cows milk n lactose intolerance n was treated got them first. It does sound to me like your baby may have silent reflux. I'd see your dr about it
My ex 23 weeker does this when she's fussy. I usually calm her down by holding her swaddled upright after she feeds. She's also on Neosure and we were told not to switch her formula because it is hard on their tummies.
My son had the same thing I had to switxh him to soy formual