Suggest Treatment For Difficulty In Breathing

Hi doc. Right now, my son can't easily breathe when he is laying down. When i asked him to feel if his chest is affected he answered NO. He said that the problem he feels is only from his nose. When I checked it, there is a small passage of airway. I am confused if it is inflammed. I don't know if he is suffering from rhinitis right now. That's why i can't give him medication. I just ask him to lay down and head tilted. As far as his history is concern.. He has an asthma acquired from allergic rhinitis and aggravation of food with MSG, chicken, egg, etc. Hope you could help me give him a remedy. Thank you.