Charlotte had croup not long ago - scary stuff isnt it!
I was told that it will pass in a few days, Charlottes lasted all up about a week.

If she is coughing and then vomitting I would make sure she actually has croup and not whooping cough, as the spewing shouldnt be happening so often if it is just croup (according to my doctor)

Anyway, lots of fluids and euclyptus and lavender rubs helped here, also raise the cot mattress up at one end so they arent lying flat when trying to sleep.

Good luck and I hope the little one is better soon