Need help for

I have 3 yrs kid suffers with mouth breathing for last 4 months. We consulted her pediatric dr. Told that she has allergy, after we consulted ENT dr told us to remove tonsils and adenoids is the only solution. We really worried about my baby and went to another pediatric dr for 2nd opinion abut surgery. This doctor is simple and good, he tested my baby again and he told me that no need for surgery but she has little enlarged tonsils. But my baby still mouth breathing. Full day she takes breath through the mouth. She she cold for last 6 months, dr told that she has allergy, at night time she suffers a lot to take breath, snoring, some times cough, runny nose. She feels difficult to take breath at night time. Plz help my kid.