It's not good that she is coughing. I suggest you consider prednisone to reduce the lung inflammation.
Also, the lungs getting involved is where the worst dangers for Covid lie. I've known several people who had lingering Covid which got to the lungs and then a secondary pneumonia developed. Maybe push to get her lungs examined? Don't ignore that very long!
Also, here are some other things you may wish to experiment with: https://covid19criticalcare.com/treatment-protocols/i-care/