Hi, Welcome to Healthcaremagic. I had gone through your question I can understand your concern about light headeedness. As per your history it seem to me you are having sinusitis. As the mucus of sinusitis is either think yellow or green. Sinusitis also present with light headache and headache gets aggravated when you keen forward. If you have the upper symptoms also associated with face tightness then my opinion is sinusitis. You must have hot steam inhalations through nose, an antibiotic course. You should consult a practitioner and take antibiotics like Amoxicillin clavulinic acid for ten days in consultation with your doctor. Saline nasal irrigation and intranasal corticosteroid may also be used. Hope the answer to your query, revert back to us if you feel any further assistance needed. Regards Dr Muzaffer Hussain Parray.