What is the thing about the SF cough that is so awful?

[Pennies]

DD (3yrs) seems to have flu-like symptoms and has a dry cough but it is causing her a lot of distress - it makes her ask for a sick bowl and makes her cry. I've seen on other threads about SF that there is an awful cough and whilst her's isn't a persistent one and isn't heavy for phlegmy at all either. What was The Cough like for other SF sufferers?

DH and all of the kids (x3) had it.

The cough was very painful and tight to start with.

As the flu progressed and the fever started to subside the coughs became very "wet" and persistent. DH coughed for at least 6 weeks from onset of symptoms (the kids for slightly less).

The most obvious consistent symptom for my family was extreme exhaustion and high fever.

The DC were sleeping 19-22 hours a day and only awake for at most 30 minutes a time for a good week. DH was in bed for straight 4 days without actually getting up. They all ran 39.5+ fevers for 5 days or more.