Hello and hope you are doing well.
Your symptoms of bad smell and nasal particles could be due to sinusitis. The best way to get to the bottom of your sinus issues is to see an ENT. A good examination inside the nose with a camera might give the ENT more information as well as a CT scan of the sinuses. If it is a chronic sinus infection, 4-6 weeks of antibiotics are pretty standard in addition to nasal steroid sprays, oral steroids, and salt water irrigations of the sinuses. If this fails to solve the problem, sinus surgery is usually recommended.
Hope this helped and do keep us posted.