https://www.youtube.com/watch?v=bBkGDIeQwXo
A London doctor gives advice on relieving breathing difficulties from Covid-19. I have linked the copy which has been provided by the BBC to ensure that this has the credibility of the BBC behind it.
Good breathing technique is a basic principle of Yoga, even for when we are fit and well. I include various elements of breathing technique in my classes, and you can continue to practice these at home when convenient for you.