My son's nose has been stuffy lately. The mucus doesn't run, but only …

My son's nose has been stuffy lately. The mucus doesn't run, but only dried crusty discharge. I spray Aqua Maris in his nose during the day and clean it with cotton swabs. It fills up again at night and in the morning his nose is stuffed again. The pediatrician said that this was due to changes in room temperature. And my own nose also gets stuffy. We got a vaccination yesterday, so we can't go to an ENT doctor yet. Has anyone experienced this? What could be causing it?