J.H.
First, DO NOT GIVE HER HONEY! It is terrible for babies (children are fine) and can cause lifelong problems. I don't mean to yell (with caps :) but it can ebe very dangerous, especially for one so young. I would try to elevate her mattress. My youngest daughter, now 1 year old, was born November of last year and had a cough until April. We tried various things. She got the most sleep and the most restful sleep when her mattress was elevated. I put a blanket under the mattress at one end so that end was higher. It helped things drain for her. Just listen to her breathing and watch that. My daughter's did not start out bad but progressive got worse. I tend to not be a worrier, as she was the 4th, but did listen and noted as it was more labored breathing and sounded wheezier. We finally had to do breathing treatments to get the last to clear up. Happy to report everything is fine now! Good luck!!