I would supplement with vitamin A, C, D, iodine and zinc. You can get vitamins A and D from cod liver oil which is ideal as they are fat soluble. Make sure to take zinc on a full stomach as it can be an irritant. Dulse seaweed has an insane amount of iodine. Make bone broth too.
Dr. Brownstein has a very successful covid protocol which has of course been highly censored but I bet it would be helpful for any kind of respiratory condition. Here is a good summary: https://sambentleygraphics.weebly.com/blog/nebulized-peroxide-a-simple-treatment-for-covid-19
(post is archived)