My kids have had a ton of croup!
My daughter had it a couple times before she turned 2. So I was pretty blase when my son got it at 3 weeks old... BTW, that's actually bad. You should ALWAYS take a croupy newborn in to the emergency room. I didn't know. My baby was fine, but the doctor gave me a piece of his mind when he saw him next.
For us, the cough and the fever always came hand in hand. I could see it coming - during the day the child would be hot to the touch, and lethargic, and their nose would be running with clear watery snot. And then that night, at some point we'd wake up because the child would be barking like a seal. When it's really bad, though, the child doesn't hardly make any noise at all - just sits straight up, wheezing, with the cords of their neck popping out. I don't know what woke me up on nights like that - but somehow I always knew.
We mostly treated at home with Tylenol and steam from the shower and cold air. (During the summer, you can have them sit with their head in the freezer - yes, it works!)
The only time I ever took a child in to Emergency for it was when my son was turning 10. He got croup so bad that I could see his stomach sucking up under his ribs as he tried to breathe, and his lips turned pale bluish/white. I took him right in, they nebulized him... and then sent him home. That was a very scary night - the poor kid couldn't lie down or sleep and ended up sitting up in a chair all night trying to breathe. This time my doctor was angry with the hospital, instead of me!

He said they should have admitted the boy for the night, that sending him home was very dangerous.
Don't let anyone ever tell you older kids don't get croup. They do. My daughter even had a little bout of it that year, and she was 12.
Anyway, my point is, croup is definitely something to take seriously. But there's usually no need to rush straight to the emergency room - or even see a doctor, as long as it's just coughing. Look at your child. How's your child's colour? Is your child able to breathe in between the coughing jags? Is your child sucking her stomach in under her ribs and flaring her nostrils, when she breathes? If that's the case, get her to Emergency. Otherwise, wrap her in a blanket and sit outside if it's winter - that works fastest. Alternatively, turn on the hot water in the bathroom and sit on the toilet with her while the room fills with steam. That helps, too, but not as much as cold air. The coughing jags usually come in waves - the child will be in distress for awhile, and then the child will get better and breathe easier. A bout of croupy coughing usually doesn't last more than a half hour, but it can keep coming back all night.
Humidifiers in the bedroom help, just make sure it's clean so you're not filling the air with molds and stuff that might aggravate your child's breathing.
Good luck! I hope your daughter doesn't get it too often.