@celia16 The CT scan could be a diagnostic tool to simply rule out a lung related issue when symptoms have included excessive mucus, nasal congestion, drainage issues, possibly hoarse voice, sinus issues and a cough. Sounds like you are feeling well though ( you’re not fatigued, not dealing with infections ) except for the more upper respiratory symptoms you mention. Post nasal drip can be frustrating. Perhaps you already use a nasal spray prescribed by your doctor. They can help alleviate symptoms.

I have no medical training, so the advice is simply not to let symptoms linger too long without a diagnosis. A CT scan might be an option, especially if you have more infections and a lingering cough.
All the best.