Doc... My Son Is 7 Yrs Old N For D

doc... my son is 7 yrs old n for d past 2 month he had some breathing difficulty. i feel that there is some growth in his nose(polyps) bt wen i consult an ent spl he said tat due to some allergic reactions sidebones of the nose get bigger n there is nothing to worry. bt my son is still suffering... i consult a paediatrician too ... bt his condition is same for the last 2 months. wen his nose get blocked i ask him to blow d nose ... green/yellowish colour phlegm is always present.after blowing he get little relief... wats d pblm doc???? whom shld i consult??? plz help me .....