N.R.
Elevate her matress at night with a pillow underneath. The post nasal drip is probably causing her hacking. IF it sounds like a rattle in her chest it could be going into brochitis.
Keep an eye on that.
My son had the NEVER ENDING COUGH for MONTHS----found out he has asthma....never weezed but he coughs when he gets a flare up.
Pollen is getting thicker with plants blooming...just a thought.