Constitutional effect???

Hello everyone. I'm new here, but have been using homeopath's for about 12yrs. But have come across something that must be a clue somewhere. My daughter who is 11 yrs. Has had a sever cough for about three weeks. It came on suddenly, no prior cold, no nasal drainage, fever normal cold signs completly absent. Just a dry barking continous cough. When she is not coughing she is the picture of health. We are having some success in treating it with Drosera, and Petussinum (sp?)
But here is what is throwing me some. Her cough is worse when alone,or in fear. But it is better by talking and by being creatively mentally active. Not just doing rote work. It must be something creative. She has also had a lot of gas since the cough began. She is fair skinned thin, short stature, Dark hair, fair eye's. She is highly intellegent. Very questioning of everything.

I can not find constitutional info for pertussnium. Her betters and worse are so striking that I can only assume they are keys. If this sounds familiar to anyone let me know.