Using a decongestant spray like Otrivin for years often causes rebound congestion. This is called rhinitis medicamentosa, where your nose depends on the spray to stay open and swells up worse without it. It's very treatable, but stopping suddenly usually makes the congestion worse for a while.
Next Steps
The usual approach is a gradual taper. Stop one nostril first while switching to a saline nasal rinse and a steroid nasal spray to calm your nose down, over several weeks. An ENT specialist can set up this tapering plan and check if allergies are contributing too.
Health Tips
Don't stop and restart the spray again and again, since that cycle keeps the dependency going. Please consult an ENT specialist to guide the taper.