Constant throat clearing can occur because of various reasons such as reflux laryngopharyngitis which is type of acidity related disorder, post nasal discharge which can occur secondary to chronic sinusitis, chronic laryngitis etc. DNS is unlikely to be the cause. You may need to get a endoscopy and CT scan of paranasal sinuses to identify the cause
Next Steps
Consult nearby ENT specialist for confirmation of diagnosis and appropriate treatment if required