Cough attack once a day

My 4.5 year old son has been having this cough attack for several months starting this year.  He usually starts the cough at 8:30 pm or 9:00 pm before he goes to bed.  Once the cough starts, it lasts for an hour or hour and a half.  Then it comes to a stop.  He is completely normal during the day.  No cold or flu symptons at all.  The cough attacks comes every two to three days.   Strange thing is that when he has a cold (having runny nose or stuffy nose), the cough attack disappear.  Therefore, he is fine for couple of weeks when he has runny nose.  When he is recovered from a cold, the cough attacks comes back.  He had X-ray taken twice, tried claritin, singular, anti-biotic, abeturol and steriod spray.  None of those work.  He just had an attack last night before he went to bed at 10:00 pm.  After he fell asleep, he is fine.  I feel so heartbreaking whenever I hear him cough.  It has been several months.  There is no answer.  Please, please help.  I already made an appointment to see a pediatric allergy next week. I am not sure I will get an answer.

[abby84]

I would check for reflux. Childern today are having more problems with reflux. Also, have him checked for food allergies. See if you can pin point what might be different such as, food that evening, milk, tomatoes, and **(chocolate)** for example. Then think about the type of blanket and detergent he has on his bed. Temperature in the room and dust. Did the x-ray show asthma? He can also have a breathing test done. Also, check for sinus the sinus cavities set back above the throat and some people don't realize they drain more at night. What i mean is the drainage is going down the back of his throat and it could be choking him when he is laying down. Not all people have a lot coming out of the nose sometimes it will go through the throat. Is the reason when he is sick it stops is because one of the medications he is taking is suppressing the cough or drying the congestion up, or Inhaler?