I've been dealing with this really bad cough for almost 20 days now. It's mostly at night and comes with mild yellow sputum. Sometimes, the coughing gets so bad that I feel breathless, and its tough to even sit up straight. I havent had any fever, body pain, or other symptoms like COVID-19, and I havent traveled or been in contact with anyone who could've been sick. Ive tried nebulizers, steam, gargling, but nothing seems to help. What could be causing this, and how can I find some relief?