Re: coughing with no other symptoms 9 year old child
I had the same thing for many years in my childhood. I was constantly coughing to the point where my throat was raw and sore. Sometimes I had a hard time taking a breath through my mouth because phlegm clogged my throat. It turned out I had acute bronchitis and an allergic reaction to freshly-cut grass. My only symptom was coughing...I had no rashes or outbreaks from the allergy. I needed a vaporizer in my bedroom at night so I could breathe, and I would cough all day and night.
I was given inhalers for this, which were annoying. The inhalers did nothing for me, but my coughing eventually went away. Even now, over 10 years later, there are times when my sinuses will drain, clogging my throat, and making my voice very hoarse until I clear my throat. It's embarrassing to speak when this happens.
I wish I could tell you that I know what your daughter has to reassure you, but I can't diagnose anything. Your best bet would be to just take her to the doctor, and they will do some tests to find out what's going on. No one gets a "hairball" in their throat for no reason.
Good luck to you both - I pray you find out what's wrong soon. If your daughter is suffering like I did, my heart goes out to her.