A lot of kids have problems and grow out of it. Allergies, snot all the time common with young kids. Been there done that. Tonsils and adenoids are there for a reason. Sounds like possobly allergies. May need to get allergy test done and 2or3 opinions with surgery being last option. They say surgery will have to be repeated for sinuses if you start as well balloon in nose. If you can get through 3 or 4 more years may see improvement.