BEST working childrens cough medicine?!

Over the counter? My daughter (5) has a horrible incessant cough that is making her cough the the point of gagging and keeping her up at night. It’s holiday weekend and her dr a few days ago wasn’t concerned about needing to treat her with anything but her cough is just awful and she needs relief. I’ve tried zarbees because it’s always worked well and it’s working sometimes but not during these terrible fits.