2 month old preemie with cough

my LO has been having this dry cough for a week and a half and the nurses at the Pedi office says there is nothing i can do. I have the humidifier on all the time around her and she sneezes like 5 times in a row..maybe its allergies but im taking her in to see her Dr next week. she seems to not be bothered by it but I dont want to risk it.