A.L.
My son had the same problem. Started sbout the same age. Saline and a humidifier worked sometimes but other times, he was still congested and snoring so much. Per the doctor's suggestion, we tried children's clariten and Zyrtec but that didn't really wok. When the snoring got worse (sleep apnea), we saw an ENT. My son had the biggest tonsils and the ENT said his adenoids were likely enlarged as well. Once they were removed, his breathing was so much better. it was like night and day! So just keep this in mind if things don't get 100% better.