What you're describing sounds more like allergic rhinitis than true sinusitis, since you have no facial pain or headache and it clearly tracks with dust exposure. The sticky, stringy white discharge and repeated sneezing fit a dust-triggered allergy rather than an infection. It can run on for years and isn't dangerous, but it responds far better to avoiding triggers than to any single quick cure.
Next Steps
A simple saline nasal rinse daily can clear the stickiness better than oiling. Reducing dust around blankets and bedding, and an ENT or physician visit to confirm the diagnosis and suggest a suitable antihistamine, will help more than home remedies alone.
Health Tips
See a doctor if you develop facial pain, thick yellow or green discharge, fever, or worsening symptoms despite avoiding dust, since that can mean a sinus infection needing different treatment.