[R Flair]

My guess would be its totally a side effect of some more serious medication that she absolutely has to take or she'll die. I have bad allergies, and I know people with extreme allergies including close family members, and those symptoms are abnormal.

You can know whatever is causing it, its unavoidable because any normal cough, even from normal sickness, can be suppressed with medication. Unless whats causing it is the medication for something else...