My daughter is almost 5 months old and for almost a week she's had a really nasty nighttime cough, the the extent I'm having to lift her up so she's not chocking, during the day she's fine hardly coughing at all but the minute she's settling for the night she's coughing awful, I thought maybe it was a laying flat thing but even for daytime naps she's not doing it.. time to call the doctor I think but I'm in two mind as like I said she's fine all day long..