constant runny nose

[Danny6]

My son has had a runny nose and nasal congestion for what seems like forever.  He had RSV 5 months ago and the runny nose just never seemed to clear. I have taken him to several allergists and am really frustrated. They have all told me that a 1 year old wouldn't show signs of seasonal allergies this young. His skin test for other allergies (mold, dust, dairy) came back normal. His immune deficiency tests were fine too. We have tried Nasonex, Zyrtec and several rounds of antibiotics. Nothing seems to work....only clears up for a few days and comes back. I am worried that there is something we are missing.

Other than the nasal issues he is fine. He is the happiest boy you've ever met...seems to have no idea that he can't breathe well and always has nasal discharge. We can't seem to identify any other symtoms and thus the doctors keep ruling out allergies and intolerances. One doc. mentioned the possibility of silent reflux but said it is hard to diagnose b.c the symtoms aren't apparent.  He loves to eat, doesn't appear fussy or uncomfortable during or after and didn't have severe reflux as a baby (only went thru a stage but it cleared on its own). Any ideas????????