Patient reports sudden shortness of breath for the last 4-5 days, requiring forced deep breaths for temporary relief. Senses a thick, heavy buildup of mucus in the airways without an active cough. History of severe respiratory allergy 3 years ago (Serum IgE: 506 IU/mL). Works in a hotel (1 year, asymptomatic), but symptoms started within 20 days of using a liquid mosquito vaporizer overnight in a completely closed, unventilated room. Self-restarted old prescription of Acebrophylline 200mg SR this morning with mild relief, but chest tightness persists. No fever. Seeking expert guidance on treatment.