"I experience prolonged, recurring unilateral nasal congestion. Is this condition dangerous, and when should I see a doctor?" asks Kien Vu, 35, from Dong Nai.

I often feel dizzy, a spinning sensation, whenever I tilt my head back or turn over, lasting a few seconds. What illness is this, is it a vestibular disorder? (Kim Ngan, 35, TP HCM)