Hopefully if he doesn't develop any further complications, the lung involvement is likely to be subsided spontaneously or may be mild damage may persists which will not create any problem in living a healthy life.
Regarding medicines, these medicines are assumed to be standard for covid treatment.
If your doctor didn't prescribe any medication it must have some reason.
It takes a lot of knowledge and confidence in medical science to not to prescribe any medicine.
Next Steps
Can take second opinion in practo. Choose your doctor as per your wish.