There are few common causes of short duration nose block which includes Allergies, Acute Sinusitis, Common cold flu.
Long duration nasal block has to be investigated, which can be due to Deviated Nasal Septum, Inferior turbinates hypertrophy, Nasal polyp and other Sinonasal pathologies. Best way to find out is through CT PNS after completing an antibiotic course after recommendation of ENT specialist.
Kindly do not use NASAL SPRAY available over the counter without medical advice for more than 10 days at it may further lead to more nasal block, condition is called Rhinitis Medicamentosa.
Next Steps
ENT Consultation online or in clinic