coughing

every time miss two runs around she starts to cough she dosent have a cold or anything she have been doing it since she could run like when she was one. the doc gave me a inhaler to try on her but if i stop her and give her the inhaler she will stop coughing till she starts running again. but then she stops coughing when she stops running anyways she runs alot verrrrry active little girl. just woundering if anyone elces kids have this or what you guys think.