How long have you had her, and are you keeping her in quarantine for at least 30 days, so your other chickens are not at risk of catching something. I would check her nostrils to make sure they are clean with no drainage, and look for any bubbles or drainage in an eye. If she is sneezing every few minutes, it could be an environmental irritant such as dust, mold, or powdery feed. But it also could be a sign of infectious bronchitis, the most common respiratory disease in chickens. IB lasts about a month, and may spread rapidly thougb a flock. The main symptoms are sneezing and some congestion, and sometimes wrinkled eggshells.