Help!

My bb is 8 months old. He has occasional cough/nasal congestion for the past week. Usually more significant in the morning, after he wakes up. Recently, he has been coughing/nose congestion more often and has problem sleeping well at night. I have cleared most(if not, all) mucus in his nose, but I can still hear mucus (maybe his cough). What else can I do so that he can sleep well at night?