Hello, Cold (viral infections) plus dust allergy can manifest with all the symptoms you have described. Recurrent sneezing attacks can also make one feel giddy. Disturbed sleep due to dust mite allergy can also lead to several non-specific symptoms. If the neurologist and chest physicians have not found anything alarming, I would suggest you get either blood tests (specific IgE) or skin test that would reveal your allergies and according start the treatment. Smoking can lead to restricted lung volumes with air trapping known as chronic obstructive airways disease for which several inhalers are available. For allergy treatment, combined use of oral antihisamines and nasal sprays will help overcome the symptoms but should be used continuously for at least 2 months or longer depending on the sensitization profile. Thanks.