He may need a steroid. My brother recently caught covid and a steroid was the only thing that helped with his cough. If you’re in the US, he can likely do a telemed appt and pick up a steroid in the next couple hours. Also, my daughter has asthma. She sometimes needs a steroid to get over her sicknesses. Do you have a nebulizer? Nebulizing the albuteral will get it deeper into the lungs. A nebulizer can be purchased on Amazon, if you don’t have one. If he has asthma, he should always have a nebulizer on hand. His doctor will need to call in the nebulized albuteral solution. And Try eating a tablespoon of honey every couple hours. Honey coats the bronchial tubes and throat. If he doesn’t normally take vitamin D, he may want to take 10K a day for the next 3 weeks, to get his level up. Then 5K a day forever, for maintenance. Get D levels checked in near future. Optimal level is 60-100.