Could be a cold, if so it'll run it's course. Just keep using the sucker to keep the nose clear.
Try having him in the bathroom with hot steamy shower running, the steam sometimes helps but with him being young you have to be careful to not overheat him. Don't put him in the water.
Just sit in there with the steam.
But he could have allergies too. Vacuum the carpets and drapes.
Keep pets out of his room.
And see if you can put Vicks in a vaporizer.
But clear it with your pediatrician.