My 7-year-old has been snoring for years, but recently it got worse. He snores very loudly and every night. He is restless at night, and wakes up very tired each morning. I heard him stop breathing in the middle of the night a couple of times maybe for about 5-10 seconds. Then, he would make a gurgling sound, snore, and resume breathing. He has not had any illnesses since last winter. What could cause his snoring?