My lo is 5 weeks old and typically will fall asleep after say 20 mins of lying on his back behaving perfectly normally, be quietly asleep for 5 mins and then start thrutching and grunting. I always make sure I wind him before putting him down although when I get him out and burp him again he is usually sick. I can't understand it as he lies there playing perfectly happily beforehand.
everyone insists its just wind, but why when he falls asleep?