Hi You have not mentioned about the duration of symptoms and how long you have been nebulizing him. Dry cough which is more at nights and early mornings indicates that he has a wheeze and that should be taken care by the Nebulization. But the technique of nebulization must be correct. For the blocked nose, saline nasal drops will do. Steam inhalation will also help. How ever if he snores during sleep or has a blocked nosy sound during sleep, its better to get his adenoids checked. For 8 yrs, his weight is more. Weight reduction is also needed. Encourage out door activities more, less of tv viewing, less of computer games and no to junk food. If after adequate treatment too, his symptoms have not improved, please visit your doctor again. Hope my answer helps. wish your son good health.