I'm trying to figure out why for the past few nights but not every night my 7 mo old who never wakes at night is suddenly waking an hour or so after putting him to bed. One night he was gassy or when I pick him up he burps. I've been trying to burp him after bottle before bed but I haven't burped him in a long time and he hasn't had any issues until this past week. Could there be another reason? Thanks