T.B.
Does she have a fever? It could be a sinus infection. Doctors will tell you that it is rare in children, but if you read anything about asthma... sinus infections and asthma go hand in hand. Generally Albuteral is used to treat children with symptoms of asthma. Have you taken her to see an pediatric allergist/pulmonary doctor?
They only other thing that I can think of that would cause a foul smell is if she is a toddler... maybe she stuck something up her nose?