My son, 35 and healthy, seems to get a dryness inside his nose often, uses ayr gel and gets better, i heard about sjogrens and i'm worried, could a dry nose be the only symptom of this? he has no other symptoms at all?

No, Sjogren's syndrome does not cause dry nose. If symptom get worse when the humidity is low, he needs a humidifier in his room and keep humidity above 30% all the time.

No, Sjogren's syndrome is an autoimmune condition involving an immune attack of exocrine glands (tissues that secrete substances in your body such as tears or saliva) that causes damage to them and decreases their ability to secrete these substances. There are no glands in your nose that secrete fluid and are not under attack. Breathing relatively dry air makes your nose dry.