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My son had this issue and my dr said it was because he was uncomfortable dealing with acid reflux. What helped him was ensuring that he was sitting upright 45 minutes after a feeding and she put him on some meds that helped.
My first was the same, so is my second. It’s quite normal, they grow out of it eventually. When my first born was able to roll and sleep on his tummy, he started sleeping through on his bassinet.
Have you taught about letting him sleep on his stomach yet? It might help.
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