Louise
Its good you are going to see an ENT because the problem could be very well due to adenoid/tonsils. After a series of sleeping and speech problems since birth, our 3.5 year old finally had his tonsils/adenoids(as much tissue as possible) removed. First as an infant he had recurrent ear infections then ear tubes were placed, and adenoids were (partially {probably because of his age}) removed at age 1.5. He continued to have symptoms of sleep apnea, lethargy, and increasing temper tantrums during the day, so the doctor finally discovered his tonsils were also enlarged and needed to be removed. A mandatory sleep study was done to confirm this. The tonsils and remaining adenoid tissue was removed, and now my son has better temperment and sleeps better we have even noticed a couple of growth spurts because he was really little in stature for his age. I can barely hear him breath now while he is sleeping. He used to snore awful. His speech also improved after having a frenectomy (tissue beneath the tongue cauterized). He had a genetic "tonguetie" disorder that caused his speech to be affected. Hope this helps.