Noted the detailed history about surgery and inability to breath properly in spite of septal surgery in your son who is 19. Also noted the incomplete removal of deviated septum for some anatomical reasons.
Hence I would advise you the following:
First of all insist on CT scan
of the nose and sinuses
o know the exact problems.
Consult after finding an ENT Surgeon who has done a lot of such surgeries and discuss in detail.
Yes it is possible that there is some anatomical deviation from normas but this is true in every case.
About the allergies and the nasal condition: Stop using any oils or so.
will show what is required as per the condition of the mucosa.
Decongestants and steroid
if the mucosa is edematous.
Sodabicarb nasal washes if there is a lot of scab formation.
Since the boy is 19 now all sort of surgeries will be more beneficial.
Hope I have answered your query. Let me know if I can assist you further.
Dr. T. Chandrakant,
ENT & General Surgeon