Advice to help 3yr olds cough

Hi everyone I'm here asking for advice on what to try to help my daughters cough every since we all had covid last year she has had a bad cough that has not stopped and when she gets a cold or any type of illness the poor thing is in like a constant cough attack I've tried a bunch of different cold and cough medicine for her I've reached out to her doctor multiple times and all they say is she's to younge for medicine and that there's nothing they can do I plan on takeing her to imidiate care tomorrow but want advice on what else I could try